Break up or not?

My boyfriend got drunk with a friend and called up exes along with other girls. With an ex he was saying I love you and miss you to her and with her and everyone else it was sexual. I just don't know what I'm suppose to think and I don't want to over react but I also don't want to under react. I am famous for letting crappy guys get away with stuff they shouldn't bc I try to see the better in people.