Why does my ex keep coming back to me?

My ex boyfriend moved out of our house and broke up with me so that he could move in with his brother, party and date a 20 year old (he's 38). He says he was going through a midlife crisis. After 2 months he was begging to come home. I can not forgive or forget the pain he caused me or the betrayal. I have been telling him to get lost for 2 months now. he will let about 1 week go by then he is blowing up my phone again. He says he talks to other girls but will always love me. He wants me to stay in his life so we can see how things go. He is worried that It will never work out because I cant forgive and he cant take it back. But, I can forgive If he can just verbally explain what really happened. I want him to show the world and all those women that I am #1, If he can do that than we can start working it out. Until then, I keep telling him to get lost and he keeps coming back. Why cant he just atone for his wrong doing and fix this so we can just get back together? I told him to add me back on his myspace and make me #1. He has been ignoring my friend request so I told him to F..k off again. It is something so simple, yet he cant do it. Makes me uneasy. Am I trippin or does this seem fishy.