Please explain why I miss someone so much that was such a jerk!

I'm gonna lay it on the table. Hes an asshole! He cheated, lied, and didn't pay me back putting me in financial trouble so why do I miss him so much since I removed him from my life? I'm not sure how much truth ever came out of his mouth. Why cant I just forget him? Why do I still feel so empty? Its crazy that I can't even imagine myself with someone else and he has had 3 relationships after me that I know of. Give me some GOOD advice on how to finally let go!! Last time I finally let go he contacted me again after 6 months and we were friends or maybe not for 15 months. June 1st is the last time I saw him and I completely removed him from my life Aug 1st. I just need some advice that works so I can get him out of my head!!!!