I hope this insecurity of yours doesn't rear its ugly head in other areas of your relationship, lawman. It's bound to destroy you in time, if you don't get a hold of yourself.
EmeraldDreams is right about one thing: if you can't get over this, you need to break up. She has a right to have a relationship with someone less insecure, and more emotionally healthy (assuming she is unaware of this shortcoming).
Relax... I'll need some information first. Just the basic facts - can you show me where it hurts?