To late to give 'us' another go?

This guy, 23 and I, 20 have were together for 10 months but we always liked each other for about a year before that but we were involved in other relationships. Anyway he is close friends with two of his ex girlfriends, they have been for ages and it is hard for me, i try to be really good about it and they talk and hang out often. But then he disrespected me and we broke up he begged me back for ages but I got drunk and slept with my ex. We still got back together trying to work through the fact that he is best friends with his first love and more recent ex girlfriend and the stress I feel and he deals with the fact I slept with my ex (Whom I never hang out or speak to while we are together apart from that time) went on a holiday together was great then back to reality and i found out he began to hide little text messages and lie to me about the ex gfs, nothing sexual or bad but the fact hed go to the effort to lie about it. Then I wasnt sure if i could do it anymore and I kissed a guy when I was really drunk and out and we broke up again. Now he wants another shot to trust me again and for me to try and deal with stressing about the girls. Advice.