Things are so complicated

I love my family, my friends, and the people around me. But it has always been hard for me to communicate and talk to people. I have gotten much better at it, but I still struggle plenty with it. A friendship I had with a girl a few years ago has affected me badly and will continue to do so, as for the fact she was mentally and physically abusive. But I have learned so much about myself from that horrible time and I am so much stronger than I was before, and I am incredibly proud of myself for that. But now it is happening all over again. This girl I've now been friends with for a year or so is now affecting me in a similar way. She isn't physical, and the threats aren't the same, but I never thought I could be so badly affected. She is very insecure, and I have done all in my power to help her through things and through her problems, but I have also had to explain to her that I'm not good at comforting people and I never have been. I have tried to make it clear that I can't always promise I will be able to give her the answer she wants to hear. It was okay at first, until I realized that my advice and reassurance was being completely ignored as she continued to vent to me. And now it has just gotten to the point where I cant do it anymore. The few times I've actually tried to open up to her, she ended up making it about her and her problems. After my first friendship I began to bottle all my emotions, and now I am back to doing that. As I have fallen badly into my depression things have only gotten so much worse. I've explained so many times that I'm not doing well and that I cant promise she can depend on me for her problems. But as usual, she ignores this and she continues to push her problems on to me, and I have no clue how to respond, as I've tried to explain before. She wants deep intricate advice about things I know nothing about, and I simply cant give that to her. As much as I try to comfort her in some way when she has a problem, my answers are never good enough, and then I am either blamed for being a bad friend or I am simply guilt tripped. I have tried to explain to her how this makes me feel, but she ignores it and continues to talk about herself. She treats me differently than everybody else, and she knows it but she doesn't seem to care that much. She always hates on everything I like, and she is always insulting me. I never once have done anything like that to her, and as much as I'm not interested in the things she likes I still try to act as if I am to keep her happy. She has no clue how hard I try just to keep her happy but either way it's not the way she wants it to be. I'm so drained and I'm losing my mind. People are telling me to just cut her off but it isn't that simple. She is in every class I'm in, and I've been so nice to her all this time, I couldn't bring myself to just cutting her off. She is constantly starting arguments with me and I simply cant handle arguments. Communication is good, but these arguments are always just her complaining and me being blamed for not being the way she wants me to be. She wants to feel better than me, and I know that. She always compares herself to me and laughs at me for the things I'm bad at. I'm smart and I know I am but it gets hard when she constantly is bringing me down, I can't seem to really believe in myself as much anymore. I have a few other friends around me that mean the world to me, as they understand me and I understand them. But she gets jealous, and it makes it difficult to talk to them. It makes it difficult to talk to anyone. I've been seeing my therapist a lot more now but I still don't know what to do. I wish I could get away from all of this.