What should I do? This is ruining the relationship.?

My girlfriend had a rough upbringing (alcoholic and abusive parents, foster home) and has done a good job of not letting that get her down. But I believe, as well as just about everyone I talk to, is her fear of abandonment. She flips out whenever I want to visit friends, spend time working at my office, and goes crazy when I'm not around. There are trust issues in the relationship (I have some issues with things she's done in the past) but I have given her no reason to not trust me, but yet she still doesn't. The last straw came the other night when a friend of mine from LSU came to visit for the week. My gf got angry that I wanted to spend time with my friend (a girl btw) while she went to exercise. I can't spend time with my friends, all of my free time is with her. Its affecting my work and my overall being. I don't want to break up with her b/c it will crush her but her issues are leaving me with no other choice?