my suggestion/opinion, your bf hangs out with some nasty guys, and if he isnt stepping up to protect your dignity and privacy, he isn’t worth it. This seems like at some point, him and his buddies might try something on you, I hope you get what I mean. I would leave this situation as soon as possible.
I personally think talking about sexual stuff like that, especially ABOUT YOU, is crossing a line. Like I said, your bf is supposed to step up and defend you, your privacy, and dignity. He isnt by allowing this kind of talk to happen. If anything, he is enabling this kind of stuff. I definitely would be kicking some ass if it were happening to me.
I would take a look at yourself, and your self worth, and ask yourself, “does he really deserve me if he going to let his friends to this kind of stuff???” If I were you, the answer would be no.
You can find someone way better, and way more worth it.