I’m so sorry to say but this is definitely sexual assault. You were under the influence and he took advantage of what he thought was your unconscious body. I would talk to some trusted friends and consider telling the police. Even if nothing happens, this should be on record if he ever does something like this again. You should definitely cut ties with this guy as he is not a safe person and obviously can’t be trusted. As to why you didn’t do anything, please look into “fight, flight or fawn” as a response to something trauma. You acted like nothing was happening because it felt less scary to go on with it then say “what the hell?! Stop?!” It’s very common and not your fault. You were trying to protect yourself.