Was it my fault? Am I a bad person?

So I was with my boyfriend for 6 months I told him that I am best friends with my ex, but I never slept with him (my ex) and I’ve known him since high school we’ve been friends a lot longer and the last time we dated was 6 years ago. My boyfriend says he is uncomfortable with this and doesn’t like the fact he is in my life and that if it was him he would get rid of his ex for the sake of the relationship. We argued for almost 2 days and he went back to acting normal I guess like he had accepted it. Then the other day we went to a play area with his kids and my sister and there was a moment when he pulled me towards him and he really hurt my arm, I got mad and hit him on the head, he said he wasn’t happy with this because it was in front of his son when I know for a fact he didn’t see it as his son jumped on me and was laughing. But he’s basically used that as an excuse that and my ex to break up with me. However before that he cheated on me also but made the whole breakup my fault.