Please help me get him back after I had cheated on him and he is with a new girl :/?

I went out with this guy, I didn't take our replationship seriously. And ended up cheating on him. for many reasonsHe found out a couple months later and we broke up we started seeing eachother a week after and it was better then before, I never realised how much I loved him till I almost lost him, he kept asking me for all the details of what happened and j generally blocked it out my mind I just wanted to focus on him. To make things better, so then on new year 2011 he broke up with me again, I was gutted. We weren't seeing eachother bit we had sex pretty much on the daily still. He then started something off with this girl who had her nose in the realtionship from the start (on of the reasons I cheated on him) and it was killing me, we were still having sex while they are together, but now it's slowly stopping. I don't know what to do I'm utterly in love with him. I haven't gone near another guy since. It's been 10 months since we broke up publically I won't give up I promised I wouldn't I can't find another guy like him. He has got me so low I went into self harming and depression. But I let him cause it is my fault. I just want him back. I'm sick of all the secrecy. I just need him. I don't know what I'm supposed to do. My jealousy got the better of me on some occassions trying to ruin there relationship by showing his new gf the texts saying we are still sleeping with eachother but she refused to believe it. I generally don't know what to do I just want him back to be mine does anyone know what I can do PLEASE help me !!!!