Dealing with this Breakup

My senior year I was extremely hypomanic for the most part. This led to an increase of my alcohol and weed consumption. Before it got too wild, I connected with this girl who really resonated with me I guess. I'm also a girl and at that time I was coming to terms with the fact that I was bisexual. Our entire relationship wasn't the healthiest with her emotionally over expressive, such as crying for my attention or to get me to do something. She was also an emotional cheater who would do things like let me know each and every single person that liked her as if that was important and/or relevant. I'm no angel either. I have been fighting my own demons and for that reason I would always tell her that a relationship would not work out between us. We have broken up and gotten back together over 15 times for sure. Now that college set in, our split has become real. Essentially despite a long bit of no talking after an awful FaceTime call that ended us for three weeks, we both ended up actually being in our hometown during break at the same time. We FaceTimed in which she told me she basically still loves me and missed me a lot- yet she was also drunk as hell. I tell her the truth and how I hooked up with someone. Yeah she didn't take that the best. We got back together after a hookup. Came backvto college and we broke up again... I just don't know why I keep going back to her despite it clearly not working out at all..