How can I get her back?

If you are not together do not give her the satisfaction of knowing what you've been up to. She sounds like the type of girl who's attracted to the 'jerk' boyfriend. I think you are too nice, too easy to manipulate, and for some girls that can be boring. Right now she has you waiting there to be her ego boost when she needs a lift, which is probably often because her dude is such a prick. As much as you probably despise her dude, take a clue from him. Be less available, apparently that's what she likes. The more you make her less of a priority, the more it will bother her and make her want to be.

Tell her one night that you've got plans. (don't tell her what though, I don't care if you're staying at home and watching ufc all night) if she starts getting angry, calmly say, I don't know why this matters to you, then say its nothing big, but you gotta go, and tell her you'll talk to her later. Wait if you can for her to call you, but whatever you do, don't answer the phone that night, make her squirm. Later you can tell her you were just with the boys or something. If I were you I would do that a couple times a week, the more you show her you've got better things to do than talk to her, the more it will drive her crazy, trust me, women want to be the queen in your world, when you won't let us, we'll try to regain our position. And that puts the focus back on her coming to you, and not the other way around.