<human>: I'm sorry if formatting is wrong, this is my first time posting to this sub. 
Okay, so basically I've been dating my SO [23 M] for over a year, everything is great, I (was?) really good friends with his roommate, my SO (was) really great friends with him. I stay at SO's apartment a lot and everything was generally pretty good in our whole dynamic. Until last night.
So all of us were at a party, things are going well, and I end up getting really tired and so we all go back to their apartment. My SO wanted to stay up and meet up with some people which was totally Ok with me, so he puts me to bed and leaves with his roommate (who I'll start to call Louis now for clarity.) They meet up with their friends, but then Louis decides to go back to the apartment and my SO stays out. I'm asleep while all of this is going on. And all I know is I felt my tits being massaged and after a second I open my eyes and while I was expecting to see my SO I see Louis hands under the blanket, groping my tits. I didn't say anything at first cause I didn't even know what to do. I then started screaming wtf are you doing, and he looks very embarrassed and leaves. I ended up leaving the apartment and staying at a friend's with my SO. I got a couple apology texts but I haven't answered them and I just wanted an outside opinion on what I'm / my SO are supposed to do. They live together, you know? And my SO doesn't even want to see him and I don't really want to see him either. I feel violated and very very hurt that someone who I'm supposed to be able to trust took advantage of me at my most vulnerable-alone, and sleeping. I don't even want to hear an explanation cause there isn't one...he shouldn't have come into the room, or sat on the bed, and he definitely should not have touched me...every step was just wrong. So yeah I'm just at a loss and any advice would be really appreciated. Thank you internet folks.

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<bot>: SO's roommate assaulted me while I was sleeping. Neither of us can even stand to look at him and we're just confused with how to proceed from here.