My best friend is dating my ex. Who i (kind of) cheated on... I'm not over him. Help!?

Okay. I had a relationship with this person, Troy. We started dating when i was fifteen and he was eighteen. The whole thing was actually me going to Prom with him because he didn't have a date. We had known each other for a long time because he was my oldest friend's older brother. (you may say I'm wrong about this) We had the same maturity level and after a while i could see us living together in the future. He still happened to be a virgin, as was I. One day, being stupid, i pressured him into having with me. Our parents found out, and we were forced to no longer see each other again. we continually saw each other during school, but then the summer came. because he had gotten his phone taken away, there was no communication whatsoever. i got into a ual relationship with another guy, after about three or four months. His name was Devin. at the college, I met up with Troy and felt so guilty that i blurted it all out. He was angry and hurt. He didnt talk to me at all, and then my best friend Jessica told me that she had gotten his new number. (she had been really close frineds with hm through the entire thing) I asked if i could have it, and i started talking to him. we slowly made up, and i had gained his trust again. at this point, i had a guy friend, Nathan, whom i hung out with regularly. One day... somehow, it turned into something more. I told Jessica, feeling so guilty. The next day she told me to tell him and when i asked if she told Troy, she lied to my face and said she didn't. the next day i visited Troy and he permanently broke up with me. we stopped talking for about two weeks, and i was hurting something terrible. i didnt know what to do. so i finally texted him, and he told me that he and zjessica had feelings for each other. i wanted to die right then and there. That was four months, ten fights, and a million tears ago. i feel like ill never get over him although everyone expects me to, and i get scolded for expressing my feelings. i just want to know how to get him out of my head and move on like everyone wants me to. help me.. please.