relationship advice!!!

So the guy I was talking to left me a little while back and didn't have anything to do w/ me until recently because he wanted to have sex and I did because I don't know there's just something about him that drives me crazy. I still try to get back w/ him but nothing works. Every since he left I can't look at another guy in a relationship way. Everyone tells me to give up but I still have a feeling it's gonna work. He recently told me that if I ever wanted to think about us being in a relationship that I had to change my ways and I told him I would drop every guy I talk to to have the chance to be w/ him again. I feel like I'm in a never ending battle w/ myself like no matter what things aren't gonna go anywhere. My head is telling me to stop trying so hard that if he wanted me he would be w/ me. But my heart is telling me to stay because I couldn't see myself w/ anyone else. I just don't know what to do.