So basically I (17M) was hanging out with my best friend(17M)last week as we were celebrating our last summer together before we become highschool seniors as school in our nation starts again in a few weeks.We spent last Sunday night hanging out with each other, playing videogames, Doing Tik Toks, watching anime etc at his house as his parents were away for some time.It was around 11:30 PM when we finished watching Kill la kill on his bed we decided to take a break and chill.At this moment he decided to open up to me that he had feelings from and personally came out to me and asked if we wanted to ask sex with me as he knew I was bi.At 1st I was reluctant and hesitated but we were both really horny at the moment and lust was in control of our minds.Not to mention my gf(18F)hasn’t had sex with me yet and is reluctant currently so I said yes.I took the bottom position and we both did it around for 6-7ish minutes before I unfortunately defecated all over him(We both ate ALOT during the past two hours) which made him furious and beat me until I started bleeding.He told me to put our clothes back on and said he’d drive me back to my house.The day after I tried texting him on discord in order to apologize and it didn’t go out so well .He told me if he tried to tell anyone that he beat me up I would tell my GF that I cheated on her.Not only that he wants me to have sex with him whenever he feels like it if he doesn’t want my gf to know and I after that incident don’t feel uncomfortable.I feel like a horrible person that deserves this and is powerless to fix anything and get out of this situation.What should I do?