At least she associates you with feeding, which will make catching her easier. Try putting the halter on this time and getting her used to it. Let her drag around...
The first step is figuring out where she gets the phone. Does she get an allowance and use that money? Stop her allowance. Her friends? Limit interaction with those friends....
I'd recommend you get to know her better. But before that, get to know yourself. You have to understand what she meant by "emotional" and "moody. For example, it might...
Just tell your friend you think there is a problem, she probably doesn't even know she is hurting you. Say something about it and maybe she can work on it.