Girl is indecisive and I dont know what to do?

Okay, i met this girl last year in january, we dated thoughout the semester and into the summer. She broke up with me that summer and ended up in a relationship with her ex-bf. We continuted to talk and be friends. We began to hang out at the beginning of semester and quickly became involved again. She told me that she still had feelings for me. She continued to cheat on her bf and any conversation i brought up on the subject was answered by "i dont know how to break up with him." She continued to become more and more annoyed and tired of him and broke up with him on chrismas eve. We have been unoffically dating all this time, and it feels like we are dating. We talked about our future and she wants to continue things like they are, but she doesnt want to be offical with me. She says she has been in relationships for a long time and wants to be single for awhile to figure things out for herself. She says that she is exclusive and i trust her. Should i stick around or let her go??? idk