Should we get back together? Help!?

Okay, well there's this girl, named Kelsey. We met at the beginning of the year, and became best friends really fast. But, after a few months I started to like her and we went out for about six weeks. She broke up with me because she still had feelings for her ex. I decided to give up on her because she said she would never get back with me, and I fell in love with a girl named Mikayla. But then her ex dumped her again, and we just tried staying friends and she kind of depended on me for support. But then, she admitted she still liked me and never fully was over me and I don't know if I could trust her again, but I think I still like her, what should I do?