My girlfriend hangs out with a girl that she used to crush so hard on

And I really don't like it. I makes me very uncomfortable. I really wish that it didn't make me uncomfortable but, it does. They were friends for about 8 months before her and I met. They are going to pride with a group of friends Saturday and my gf asked me to go but, I'm not going. She says they've never hooked up or kissed but it still makes me uncomfortable. I'm being too weird aren't I? Ugh, I can't help it! Am I wrong for being uncomfortable about it?