Really?

So, i have been in love with this guy for 6 years. we dated on and off and on and off. It was a very long distance relationship (as in, he lives in the UK and im in the US). Hes my best friend and everything i have ever wanted in a guy. After we started to really rekindle our romance and i really put effort into making things right with him, he started to romance with another girl closer to him. He told me he was going to date this girl and **** hit the fan. Granted that ive never talked to her, nor have i ever wanted to (shes uglier than sin, and i cant bear the thought of a beautiful boy like him being in love with such an ugly chick...), i hate her. She took him away from me and distanced him from me so much. We even stopped talking for 2 months because i was unhappy and frantic and wanting so very much to break them up. But I didnt. Their romance continued. And then all of a sudden, he comes back to me because hes sexually attracted to me and loves being around me. Hes even told me while he was with this girl that he thinks I'm still his one. And if they were to ever break up, it would be me he would want to be with again. He always talks about when he comes to visit me, how we are going to have sex everyday. This really hurts me, but i love the attention too much to let go. He wont leave this girl, and i get the feeling that even if he did come here and we did have sex, hed go back and NOTHING would change. He wouldnt come back to me, date me, or anything. Hes cheating on this girl with me, and if i told her, shed just tell him and hed yell at me for putting such thoughts in her head, like i did before their relationship really took off. Im going crazy. I dont want to pursue a guy who cheats willingly on a girl that he LEFT ME FOR. But i still love him...I know this entry is really messy, but i dont know where else to get my thoughts out at.