I’m not a great person to be asking for advice on this because a) I don’t know a lot about the psychology of rape victims and b) I, too, had a friend who was sexually abused and none of us really knew how to handle it other than being there to listen to her and encouraging her to seek therapy, which she did.
I think you should definitely talk to her about it and tell her you’re available for her to talk to if she wants. I think you should also encourage her to consider therapy or at least consider calling a phone line about it. There are distress centres and rape crisis centres and other centres along those lines that might be able to offer more useful counseling and advice to her.
You don’t need to pretend you didn’t hear her just because she was drunk and upset and might be embarrassed about her behavior. When you find out a friend is in trouble, you do your best to help them, even if they find it a bit embarrassing. That’s what I think, anyway.
If she freaks out and distances herself from you for a while when you bring it up, don’t take it personally. She’ll probably look back on you months or years later as one of the few people who reached out to her and tried to help her.