How to deal with BF not understanding your concerns

I will try to be quick because this is a long story - bf and i have been together for almost 7 months. we are both in our early 20s

1) bf dated his ex for a few years, on and off

2) their relationship was a quite open, as in they would have 3somes/orgies/date people together

3) when they broke up (she cheated on him), they kept sleeping together

4) when he and i started dating, he ended things with her

5) his job that he used to work at was a very small work environment and he and she would have to work together very often in close proximity

6) the job wasnt a career so he quit it a few months ago

7) during his time working there and after he quit, she would constantly call him to chat and gossip about work

8) eventually, i told him this cant happen anymore and he told her she cant keep calling him, but she still did... in the end he blocked her number

9) this week we have been a bit on a bump in our relationship (which is quite rare), and he mentioned that there is a slight chance that in a few months, he will work on the weekends at his old job(where she will be), to make extra money on the side.

10) i told him that i dont feel comfortable with him being around her again because she doesnt respect boundaries (she has asked him 4 months into our relationship if she can have a threesome with us. Other things like her calling during our dates and she knew he was with me)

11) IMPORTANT: i am strictly monogamous and am not interested in the lifestyle he and she had together.

12) i have been super insecure about their relationship bc its very different than how we are. she was very promiscuous and didnt have an issue flirting with other men to get free drinks, in front of him (which he said he didnt mind)

13) now, i told him that if he decides to work there again, he has to promise that he wont encourage her calling and make a boundary. i dont care if they have to work together, and i am okay with him being "friendly" with her. but she has a manipulative past and the fact that he isnt making boundaries with her so that she doesnt feel comfortable calling or asking him sexual questions really bothers me. He was super upset when i told him this, saying that i am making this about me. He said she is meaningless and he likes to hear the gossip so he doesnt mind if she calls (as he will use her for gossip), and he just wants to make money. I understand where he is coming from, but i know this girl's patterns, and if she begins to think its okay to call and be way too friendly with him, she will become dependent on him again (which already happened). And, in my opinion, thats not healthy for the future of our relationship (which i know he sees as very serious).

My concerns:

i know this come off as controlling, but i have no issue with him having friends who are girls. But, she has proven to me a few times that she doesnt respect our relationship. I want to trust him, but this is a barrier for my trust because it makes me feel like he is keeping her on the side just in case, cause she was an easy and fun sex partner he could have, and he doesnt want to completely cut ties with her. It also makes me feel like part of him misses the polyamorous lifestyle, and that i could never be enough at the end of the day. It also worries me that even though NOW he blocked her number bc she is so "meaningless", then shouldnt it be not a problem for him not to get calls from her in the future? the only thing in my head is that he likes the attention from her and wants to keep it.

Now, i for sure want to address my concerns about it, but i am scared to do it. i am scared he will get tired of my concerns (since we have had a few convos about her before). I also dont know how to bring this up without making him mad... i just want him to see my side.

Any opinions on how to deal with this?

Please don't be the rebound. You deserve to be respected.

He is obviously still have emotional connection with EX and wasn't ready to be in a new relationship.

Next time. Meet man that is truly single.

Good luck.

Honestly, I would tell my husband that in order to respect our relationship, this person needs to be out of our lives.

I had an issue, no where near the gravity of yours, with a girl who used to be close with my husband years before we got together. She’s come to a few of our parties and crossed a few boundaries of mine. I told him that I’m not willing to deal with drama and BS in my marriage, and anyone who doesn’t respect our marriage is not our friend. He hasn’t talked to her since, nor have I.

You know what your boundaries are. Enforce them or walk away.