Sweetheart I skimmed but what that cousin did to you was rape. It's not drunken sex, you could not give consent (except for cuddles). You did not even know who was doing that, you thought it was your boyfriend.
I appreciate that making a statement to the police is hard and rape cases are hard won so I will not tell you you have to do it. I just want to reiterate what that guy did was wrong and he took advantage of you but that does not make you lesser/more stupid for it.
Take care x