Why the thought of the ex-girlfriend drives me crazy?

We all know the drill about our own exes. We think about and analyse them over and over and we can usually, eventually come to some kind of constructive understanding as to why it didn’t work, what we ever saw in them, and eventually let go. We have practised this, rehearsed it and watched many another girl release boys into the background. It is the way of the ex.But what happens when you have a boy who has an ex and hasn’t managed to achieve any of these things?

I won't lie to you this is a phenomenon!Here is the thing.I always think about my syg ex-gf.I've tried to not think about his ex,but its not easy for me.I know and im telling myself that I'm being silly and paranoid.If I push the matter and i know he gets angry.The problem is that I love her so much and I keep hoping that things will improve(myself).I think it would kill me to leave, but it's killing me to stay. I just don't know what to do anymore.I keep viewing his ex profile.And comparing myself with that girl.Bt now she's not in my friends list anymore.I know this is stupid but its not easy for me to get this shit thing out of my mind.Sometime i'll get emo and didnt reply my dear msg or even pick up his call.I know that is not really quiet ok.Iam selfish.And sometimes.Im pretanding that im ok to everyone.