I dont know how to feel about this

A little over a year ago, someone who i thought was my best friend (M) decided to ask me and my gay friend (C) if we wanted to have a threesome. And you see M wasnt gay or bicurious he really didnt want anything to do with C he just wanted to have sex with me and didnt want C to feel left out since we were in C's room and drinking with him. Well after a while it ended up that C was just laying there watching M and I have sex, and everything was fine until he put it in my butt, i laughed and i told him to stop and he took it out and continued vaginally for a few minutes and then i feel him put it in again amd it hurt so i pushed him off of me and I rolled over on my back and he just lifted my legs and put it in again and i kept telling him to stop and he wouldnt, so i rolled over and tried to sit up so he couldn't do it anymore and he just pushed me against the bed and kept going until he finished. And after i just got up and went to the bathroom and cried for a bit and my butt was bleeding. And i just i dont know, whith my boyfriend i tried anal and it made me have flashbacks and to this day it still affects me. And i just cant seem to get over it, and it (along with other things) habe caused me to have serious abandonment issues that actually ruined the relationship i had with that boyfriend. I still love him and i really want help because he said in maybe a year once we both habe grown more as people we can be together but i just dont know what to do to get over this.