Search Results: getting back with someone who cheated

I need help!!! It's very complicated. Let me start from the start...
I met this guy Jesse in September and we started seeing each other. I finally felt like I found someone that actually cared about me and liked me for who I am, I was happy. So he started seeing his ex girlfriend behind my back and her and I ended up finding out he was playing both of us. He left me and ended up getting back with the ex..

So their back together.. and he was still seeing me, I was with him everyday. Practically living at his house. I was best friends with all his mates. I brought him presents. I tried so so hard to prove to him I was worthy and that I had changed from a ''player'' to someone loyal. I did change.. Because him and I were still seeing each other (Although I was a side chick, there were still feelings there). I told him you need to chose, it's either me or it's her and he chose me, and when Maddie found out, she went running back to him. I know how threatened she is of me because she knows I can give him what she can't. But him and Maddie would fight. He would come back to me. Then him and I would fight and he would go back to her.. It was a constant battle. I never know where I stand with him. Recently we had a talk, and we decided it was best to just stay friends, but there was still that tension between us, and we could never resist it. He's told me that we'll be together soon, and that he cares about me so much and he's proud of me and he sees a future with me but not Maddie. I just don't know what to do. I'm so far into his life that I can't leave. I don't have the strength or the courage to walk away. I'm in love with him. But he has a girlfriend? Do I keep fighting and trying to get him? I'm the type of girl that always fights for what she wants and I never stop till it's mine. I want to stay and fight. But there's only so much a person can do...