Ex broke up after a sustained period of weird behaviour - I'm still confused

This is a long story so bear with me:

I had been with her for a couple of years (we had been friends first and it's hard to pinpoint when it evolved into a real relationship) and for the most part things had been good. I thought she and I had clicked and I was mostly happy with her; the only things that bothered me were that she had lied about her age at the very beginning, and she had a tendency to isolate herself when things were bad, saying she didn't want to bring me down. She was in college and we were long distance, but I was prepared to work through it and I assumed she felt the same way because she had pursued me rather than the other way around. In the last year or so, she began to develop a tendency to threaten to break up when things weren't going her way, which I absolutely hated - I held off on going to see her because I didn't want to make plans and have her suddenly decide she wanted to break up, I wanted a little period of stability so I was sure. She would never tell me something was wrong before deciding she wanted to break up, and it often came out of the blue - I remember one day when she was happy and excitable and normal in the morning, and had decided she wanted to finish it by the evening. I'd ask her to talk, we would, and she would always change her mind and then afterwards would gush about how sorry she was, how much she loved me or was thankful for me, and how she didn't know what a good thing she had. I became quite frightened of her because I was in constant fear of her suddenly deciding she wanted to break up.

About eighteen months ago she had a huge falling out with her parents - she had often accused them of being distant, but had now decided they wouldn't give her space - and stormed out of the place they paid for, and went to stay in the spare room of friends, a brother and sister. The brother was almost certainly interested in my ex, who having had a sheltered Catholic upbringing and being very naive I suspect didn't pick up on. I didn't like or trust this guy at all, he liked to slip her marijuana edibles and encouraged her to do things like vape even though she's asthmatic. They would also have arguments that turned nasty, and he wasn't afraid to get physical with her. I was really limited as to how much influence I had over this because of the distance, which I hated, but she had school and I had work. She told me about this and I urged her to get out of there and patch things up with her parents, but she refused. She disappeared for a few weeks and when I tried to reach out to her she told me not to contact her until she said it was OK to; I was really hurt by her reaction but assumed it was because it was exam season and she was busy. She reappeared afterwards and things seemed fine, she was her regular self and had been to her parents' holiday house over Christmas, she wanted me to Facetime with her and send her pictures of the snow where I was. At one point she told me she wanted to get married, which I laughed at before she said she was serious, and I said we needed to think more carefully about it, which she said she understood. On New Year's Eve she told me she was going to change her phone number - she did this often, it was a common reaction for her when she'd upset someone and didn't want to talk to them anymore - and that she would text me later. She didn't.

I reached out to her via email later that week, and she told me not to contact her and that she "needs some time". She had wanted to get married two weeks earlier. I replied telling her what I had told her several times before, that I hated it when she shut herself away and that if something was wrong I wanted her to tell me. I made a lot of attempts to contact her, because I had no idea what was going on and was quite worried about her. She finally got back to me about two months later, angrily texting me to tell me to stop contacting her because she "didn't want this anymore". I tried to get answers from her that she refused to give, at one point she claimed to be pregnant from a sperm donor and tried to emotionally blackmail me, telling me that if I cared about her at all I would leave her alone. I would regard myself as a pretty placid and patient person, but I got angry and called her a "selfish, manipulative " and told her I would never forgive her for what she had done, which I regret although I don't think what I called her was necessarily inaccurate. Two days later she texted me "I really want to talk to you" followed by "Actually never mind". I tried to find out what she wanted but I didn't hear from her for another three and a half weeks, when she called me, this time claiming again that she was pregnant but this time saying it was by this male roommate/friend. Her story was full of inconsistencies and she kept giving details I had never asked for, but refusing to answer questions I asked her. I was sure she was lying and offered her a lie amnesty the next day, but she refused to admit it. I told her she had turned into one of the worst human beings I had ever met, which was maybe a little fierce but I meant it.

I gave her a while to cool off before reaching out again because I was certain she had lied and wanted to know why she was doing what she did and where I really stood, and because again, I was worried about her. She took two months to contact me again, calling me in the middle of the night and admitting that she had lied about being pregnant. She told me that her roommate would get angry over me having a relationship with her, so in order to avoid more fights (both verbal and physical) she had lied to him and told him that we had broken up and that I was obsessed and wouldn't leave her alone. Thinking that I would then expose her original lie, she decided to cut me off without warning, and when I tried to contact her to find out what was going on lied about being pregnant to make me push her away. She said sadly that I probably hated her now and had probably found someone new, and tried to put me off by telling me that she had starting vaping and drinking knowing that I hate smoking. I tried to get her to tell me what the hell was going on but when I called her again she flew off the handle because he'd thrown a fit again, crying and begging me to lie for her if he called me, all while driving and trying to blame me for everything, including her driving through a stop sign. She finally calmed down but while I was trying to get her to have a serious conversation about what was going on, our relationship and what she wanted, she just sat with a friend giggling while on the phone to me. She hung up without having really answered any of my questions.

I reached out again and she called me and told me that she had moved back with her parents and how she felt, claiming that she hadn't known what she was saying all the times she had told me she loved me before, and that she wanted to be alone and to concentrate on school. She justified all of her behaviour by saying that I "can't let go" and that she had tried to tell me she didn't want to be with me, even though she had changed her mind every time she did. After this I confronted her on something she had put on her Instagram, and she told me she had cheated on me with her roommate for eighteen months, but panicked and started begging me not to tell anyone she knew about this. When I started yelling at her she started laughing and told me it was another lie, and that "you know I like to with people", even though I had never known her to do anything like that before all of this. She asked me to Facetime with her and we said goodbye for what I thought was the last time. I was absolutely heartbroken; when she said she had wanted to get married I didn't hate the idea, I just thought it wasn't properly thought through.

A week later she called me, saying it was to "check up" on me. We talked for a good couple of hours and it felt like how it was when we were still together; she even rung off saying she had things to do and would call me back, and did. Then my phone buzzed, and she pressed me to tell her who it was. When I told her it was a female friend she snapped that she didn't want to talk to me anyway, and refused to talk when I asked her what was wrong. I asked if she was afraid of being close to people and she adamantly denied it, telling me "I can get close enough to someone to have sex with them" despite no one mentioning sex. We talked again a few weeks later and ended up having a fight because I still thought she was creating more questions than she was answering. She admitted to being jealous because she thought she meant more to me, but then had the nerve to call me a "great friend" rather than her boyfriend, which was incredibly hurtful. When I confronted her on saying she wanted us to get married, she just said "I was young", even though it had only been six months earlier, and that it was because she was going through a hard time. I hated that she was relegating our relationship to some big mistake that lasted several years. She said she wanted to concentrate on herself, as if she had done anything else in the past year. I told her that if she didn't want to talk then to stop returning my calls and to stop acting like a child. We haven't spoken since. I tried to get her to talk to me a couple of months later without us fighting by asking her to call me, and she did but I couldn't take the call; when I returned it she hung up without answering and I assume blocked my number or changed hers again.

I have no idea what to do. I was probably in the wrong for trying so much to contact her, but I just wanted to know where I stood, how she was feeling and what was going through her head when she did the things she did. Most of all I just wanted to have a conversation with her without any lying or manipulating or game playing. I'm suspicious of the way she decided she didn't want to be with me *after* she did all these bad things that she acknowledged made her manipulative and probably made me hate her, and especially of the way she got jealous and refuses to talk to me when I ask her about her real feelings. There's a large part of me that is willing to try again if she was to apologise and we could let each other know where the other stands. I miss her every day and find it hard to connect with other girls, and she's capable of being very sweet and kind and caring. On the other hand the side of her personality she showed after all of this was so obnoxious, arrogant and nasty, and I'm not sure I can ever trust her again, and how long it would be before she started pushing and pulling again. I've written her a long letter explaining how I feel and telling her all the things she wouldn't let me tell her before, but I'm afraid to send it because I can't cope with the possibility of her throwing more tantrums, or more lying and game playing, or her seeing someone else. I just feel completely lost.

Thanks for reading all this way, any input would be very much appreciated.

have you ever actually met this gal, spent time in person with her?

the undeniable thought going thru my head is this - if you have never been able to CONFIRM anythign she says by either seeing it (well.. by SEEING it in person) and see that her stories check out... my overwhelming guess is that she is one of those people that "play" online and make up stories, profiles, fake lives, and finds somebody who will listen and make it more outlandish each time jsut to see how long somebody will believe or listen or how far they can make them commit with such an outlandish story.

in other words - i think it's all fake and you've been taken for a ride. and the drama keeps getting worse because she wants to end it and is trying to find something drastic enough that you object to that you'll stop talking to her.

i'd move on.

I knew her for a long time and the weird behaviour and outlandish stories and lies didn’t start until the very end. This is just the last few months of the relationship, prior to that it was all pretty normal for the most part. One or two people have suggested she has an undiagnosed borderline personality disorder, although obviously I’m not a doctor.