I know I should break up but I can't do it.

So I've been with my girlfriend for about 1 year and 2 months now, 8 months of them have been long distance. I was skeptical about the LDR (I had been in one already and I was miserable) but I liked this girl and even though logically my mind screamed no, I said yes. It was okay at first but then I started to slowly feel sad again... I don't like the distance, I end up feeling lonely and I find myself feeling sad. The girl I'm with has done nothing wrong to me, we've had some disagreements before which were quite big in my opinion. The main argument was that she always said that she doesn't want to leave our home country and I said that I wanted to leave (I'm doing a masters abroad), so I broke up with her and that was it, for a while. We kept chatting (shouldn't have, I know) and we ended up getting together again when I had already moved away. I'm 2 years older than her (I'm 22 turning 23 and she's 20 turning 21 so IDK if this plays as a factor). After months of her saying she doesn't feel like she would really like to move here, she said she wants to, but this worries me because I really fear that she won't be happy here and she once asked (almost demanded) if I would go back home for her if she were to get home sick. I said no to this because I moved here for me and for a better life, not for anyone else. Anyway, as time went by we both started to get sad and lately it escalated a lot. We're both sad on a daily basis, and at one point we had a Skype call were we basically spent 2hours discussing how sad we are and crying in front of each other. One would say, well just break it off. While this little voice inside my head is screaming at me telling me to end it, I find myself that I just can't do it. I think about breaking up, then I realize that it would mean that I could never speak to her again and never see her and it hurts me so much that I sometimes just end up crying on my own. I'm feeling very bad, I need to break up because I don't see it working out but I also can't do it because I love her. I should have listened to myself way back when I was going to make the move and stayed broken up and now all that's happened is that we have more feelings for each other but we're also both miserable. Something else that is confusing me that even though I'm constantly sad at the thought of breaking up, I also don't feel ready to move in together if she were to move here. Mostly because I'm afraid that it wouldn't work and we would end up in an even bigger mess, but now I'm also finding myself thinking "maybe she should move here". Another issue with this is that she hasn't studied past high school and her salary here would be very low compared to the cost of living (even she has complained about this issue) and so it would be a struggle for her to cope. I don't want her to come here to have a life that's worse than the one she had, she doesn't deserve that. I've never felt like this in my life, ever. I'm always sure about what I want, but not this time. Last time I broke up I just wanted to do it and once I did I felt better. But this time I find myself crying when it really hits me what breaking up would mean. Can someone offer advice about this? I really don't know what to do and also I'm afraid of getting depressed. I have close family members that have been depressed (on more than one occasion) and I'm afraid that it will happen to me. I already feel sad almost 90% of the day and it's effecting me at school and in other places. Generally I've always found a way to cope with feeling down and I manage to quickly recover but this time I really feel stuck and don't know what to do and I feel that I'm losing my mind.

Set each other free to find local happiness in your respective locations. It seems you are both hanging on for nostalgia.

Yeah, she's just pulling you down. She's making you depressed. As Wiseman said, you should break up with her so you can date people who are at school with you. You've picked a different path in life than she has. Let her stay where she is while you keep moving forward.