listen very clearly, you need to leave him alone,,, when you guys were together at first he didnt care of what you felt, now you guys back together and he cut her out of his life, its sounds to me they was more then just friends, and that he just relized that you are better then that trick!!! You deserve better then that, she will always be around in one way or the other because of the friend circle, it will only cose dramma and have you upsad and worried either way, if he stays at home or if he goes out with these friends,,,
good luck hun