i wasn’t outright sa’d so i feel selfish for feeling like a victim of something

i (19f) was with my bf (22m) for almost 8 months at this point.

throughout the first year we knew each other before dating and the 8 months we were actually dating, he had a male best friend (21M, we’ll call him L) and was also friends with said male best friends girlfriend (21F, we’ll call her B). i never had a major problem with B, i interacted with her occasionally & the only issue i could maybe see with her was her being a little too blunt for my own taste in people i surround myself with. but she was so head over heels for L and defended him even when he was a pos, alarm bells never raised in my head that she might be a bad person.

the last few months though, my bf & B had been hanging out a lot more and he stopped telling me he was with her until i asked him myself. i found out a few months ago my bf was going to B for help with our relationship. when we would argue, when we had any problem, etc. he was with her “getting advice.” i let this go because i didn’t think it was necessarily worth picking a fight over, but i became suspicious of this girl.

fast forward to last night, she came to me over instagram to tell me that my bf has a problem about oversharing personal details regarding intimacy that should never have been shared with anyone else. we’re long distance so she said all of the information had to do with pictures/videos i’d sent him and about what i did/didn’t show, what he wished i would show, how the relationship isn’t meeting his needs, how he looks at other girls openly, & he said one of the things he’d miss if we ever broke up is something sexual about me i’m too embarrassed to even write anonymously. as far as i know, no pictures were shared with this girl but i have no way of knowing that for sure. my bf also told B’s boyfriend L. and i’m very certain that my bf and B had an emotional affair, if not a physical one but i can’t prove that either.

i don’t know what to do or how to process this betrayal of trust. i feel like i’m going fucking crazy & i feel so violated and disgusted and dehumanized. but it wasn’t sa so i feel guilty and selfish as well for feeling like i was a victim of something even though i don’t think technically what he did was wrong on the surface because he can just claim it’s normal for guys to talk about their sex lives with their friends.