How do I tell if im gay or i sorta got raped?

I think I am gay because I have an older bi friend and he keeps asking me and i gave in a long time ago to have sex with him everything but mouth to mouth eveything else and now i cant stop i dont want to but i just do i dont know why. I masterbate to girls and i dont get an errection fom guys doing anything. I just need some one to talk to please help