@Confusedgirl1234,
I wouldn't classify what happened to you as assault. It would be if you had at least once told the guy "no". He is a horny and persistent perverted jerk, but I wouldn't say rapist. He was also mislead by you and your friend. You say he was interested in your friend and was out with the both of you. You were all drinking and having fun. You had been out with him before. You suggested getting a hotel room, and your friend agreed. The guy probably thought you both wanted him. Maybe he is older and gross to you but if so why give him all the wrong signals?
If a woman that I had been out drinking with suggested getting a hotel room, and then got into bed with me, I would take it as a definite "yes". You should have made it Crystal Clear to him that there would be No Sex.
Is this is what you normally do, get drunk and get into bed with guys and then act surprised that they want to have sex with you? Is your boyfriend aware of your party habits? If my girlfriend went out drinking with another guy and then suggested getting a hotel room with him, that would be the end of our relationship, whether there was sex or not.
Does your boyfriend drink with other girls and then get into bed with them? What would you say to him if he did?
I suggest you tell your boyfriend everything. It will be painful for him but not as bad as hearing it from someone else. Also, to prevent a fight and your boyfriend possibly losing his job, make sure and tell him that you never said "no". Then, if you want to keep him as your boyfriend, beg for his forgiveness and promise never to sleep with other men. You're 25 years old. Time to start acting like an adult and taking responsibility for your actions.