I need advice

So this past summer my boyfriend and his friend Tommy got really drunk. And we were down in my boyfriends parents basement. And Andrew(my boyfriend) went upstairs to make him some food. And I was downstairs still. Well tommy comes next to me and puts his hand around my neck and starts telling me that he will kill me for Andrew and that he knows I want him to pleasure me while he’s upstairs and starts squeezing the back of my neck. And so I go upstairs and tell Andrew and he’s drunk so he doesn’t pay attention to it. So a little later Andrew decides he wants to go to his room and play xbox so I follow along and so does tommy. At this point they are annoying me bc I’m the only sober one so I go to bed. Well I turn towards the wall away from tommy and Andrew and Andrew is sitting at the foot of his bed playing and tommy is sitting next to me. I fall asleep and I’ve always been super cautious about listening to my surroundings while I’m asleep when I’m around other men. It’s just a thing I picked up on when I was younger and was abused and was almost raped at a party. So Andrew goes to pee and I open my eyes so I can be conscious in what’s going on. And out of nowhere Tommy starts rubbing and patting my butt. I freeze up because that’s just what my body does and I couldn’t move even if I wanted to because my body was in such shock that he did that. So Andrew comes out of the bathroom and tommy hears him so he of course stops and acts like nothing happened. So fast forward to the next day. I tell my boyfriend and all he says is “oh I expected him to do something like that”. And it really upset me because he didn’t even seem phased by it. And so here we are 6 months later and my boyfriend still talks to tommy and i tell him all the time it bothers me and Andrew says he just uses tommy to get free alcohol because tommy works at a liquor store. And I go through andrews phone because I don’t trust him when he lies and Tells me him and tommy don’t talk. And they text and make conversation like they’re best friends and like tommy didn’t do anything. And Andrew is still friends with tommy on Snapchat and I saw where they had been snap chatting and when I said something about it to Andrew he called me a liar and then the next time I saw him tommys messages and snapchats were suddenly deleted. I just feel betrayed and disrespected by my own boyfriend because he still talks to the asshole. And I also found out from another friend of Andrews that used to be close with tommy, that tommy is known to rape other girls when they were drunk and passed out. So I don’t get why Andrew wants to associate with someone who’s known for that. Anyways, sorry this is so long but the whole situation is just starting to bother me a lot worse to the point where I stay up crying all night Atleast 3 times a week. I just don’t know what to do.