I'm in need of relationship advice so please help!?

[Alexis]

I recently just found out that my ex boyfriend is going out with one of my friends. We just broke up not even a week ago. This is the THIRD time he's broken up with me for her. Everytime he goes out with her he ends up breaking up with her for me within two or three days, because he realizes he's "in love with me.".. It's the same story over and over again. Honestly, I have no idea why I keep going out with him. I feel like I can't get over him. It's hard to see them together, because I have to hold back the tears. I can't avoid them everytime, because I have classes with both of them. Everyone has been telling me that were just gonna get back together again, but this time I don't want that to happen. I'm tired of all of the lies and I'm tired of being hurt over and over again. I really don't think he knows what he wants. If anyone could give me ANY advice.. I would appreciate it. Thanks. (: