AIO. bf (21m) slept with his girl best friend (22f) before meeting me

To start off, I am a queer woman and my boyfriend is both transgender and bisexual. We’ve said it ourselves, we have very untraditional way of doing things.

My boyfriend and I have been dating for well over a year. On our very first date he told me he had been in a previous relationship (2022?) where he and his boyfriend would have threesomes, he told me these threesomes would happen occasionally and the downfall of their relationship was his boyfriend cheating on him with this other person. I later found out this other person was this girl he still considers his best friend.

I don’t think I realized how bad it was initially. He has told me time and time again, yes this girl is literally the reason that he and the man he was in love with broke up. Once he found out he had been cheated on he dropped her, blocked her, said he’d never speak to her again. This was one of the worst moments in his life, she’s someone who caused him so much pain. Even after all that he still reached out to her a year later asking to be friends again.

The first time I met this girl best friend she hugged me, the second time i met her she showed me her boobs in a room full of people who of course, had already seen her boobs.

As of now, this girl best friend goes to university 5 hours away. I have seen her multiple times, she comes to visit when she’s in town. A few months ago me, my bf and a few of our friends were taking a road-trip, I don’t know why but he figured he’d invite this girl best friend. Everyone in our friend group knows about this person and what they did previously so obviously the people going were not comfortable with this. No one talks to this person or likes this person and yet my bf still tries to have her around.

Prior this road trip she had come in town and slept over. That night me, my bf, her and my roommate (her ex 😱) went on a walk. My boyfriend and her in front, me and my roommate behind them. Weird how something so little can affect me so much.

I have talked to my bf about this before, I said this makes me uncomfortable, he said why, I said because you had sex with this person, he says it was in the past, I said it doesn’t matter because you’re actively talking and seeing this person. I would have had a completely different reaction if this was a girl who was no longer in his life.

4 days ago I asked if she was coming to our halloween party (she isn’t) later that day he came home from work and said she had stopped into his job because she was in town.

This has been an argument through the course of our entire relationship and I don’t know how to see it from his perspective. I can’t understand why he would let someone treat him like that and forgive her so easily. The thought of them having sex makes me sick to the stomach and I can’t unlearn what I already know. He says it doesn’t matter and it’s not relevant but I don’t know how you can look at someone you’ve had sex with and glance over it. I can’t help but know he had to have some sort of attraction to her in order to have sex. I have talked to all of my friends and they also can’t understand why she’s still around and how i’m so okay with it.

I don’t know where to go from here. Some days I firmly believe he’d choose her over me. This is a genuine root to all of our problems.

During our past arguments about this situation he has said he’d block and cut her off if it’d make me happy. That said, sometimes he’ll contradict himself and say that’s never going to happen and that I should be okay with it. The thing is, even if he did cut her out of his life I don’t think it would change how I feel, it’s be so long and this has been an ongoing issue throughout our entire relationship. He would blame me for making me cut someone off, have some sort of resentment about it. My issue is that he doesn’t see it as bad, he doesn’t realize how disrespect it is to me.

What would you do in this situation?