Think good riddance - he sounds like a complete w****r. I can imagine how you are feeling, usually when somebody is cheated upon they feel like it is a personal attack, like maybe there is a deficiency with them or that they are not attractive enough, this is not always the case though, sometimes the cheater is just a selfish idiot with a lack of self-control. Don't let his actions ruin your self-esteem. And stop spending any more minutes trying to figure him out - you will never receive the answers you require, sometimes there aren't any, forget him and move on, don't give him the satisfaction of knowing he affects you.
[SIGPIC][/SIGPIC]
Love is like a merry-go-round: you get all dizzy, and then you feel sick!