Gf not really my gf.Should i break ....again?

After a year and 4 months into my first relationship(both 20) my gf broke up with. It was the usual "I can't give you what you are looking for, and i only see us being friends." I was obviously heartbroken since this was my first actual gf. I spent my summer working and didn't have much time to think about everything that occurred. Towards the end of summer i receive a text from her saying how we haven't spoken in such a long time and seen each other. Although not together, I still miss her and still seek her affection. I spend a few months together with her and i develop all the emotions i once had for her all over again.In recent months I find out from her older sister that she likes someone else.This hurts me a little on the inside, but we still continue to see each other and she is still her lovey dovey self showing no difference towards me. During a night out with her friends, few of whom i significantly dislike(she knows of this fact), she discloses with them that she only hangs out with me because she is forced to. Not for the sake of being with me, but for the sake of doing me a favor. I want no such thing. I also learn of her flirtatious behavior with her friends whom I hate. So reddit i ask you this. Should i just call her and politely tell her i want nothing to do with her anymore and just move on? Or is there any better advice. Thank for any input on this matter.