His first love?!

My husband wants to hang out with his first love. They never dated, but they made out and would have done more if they hadn't been interrupted. Her and I do not like each other and he knows it. We fight almost every time we see each other so he doesn't want me to come when they hang out. She has cheated on every guy she has ever been with and plays victim with everything and I can't stand her. I am super pissed about this and he say's I am just being insecure.