Advice on relationships.

Me and my boyfriend have been together for a year and a half we have a son and out of no where when I’m not at his house he starts talking to others girls telling them he misses them and talks bad about me to them, but when I’m there and tell him I don’t want to be with him because it’s hurting my feelings he starts to cry and beg me to stay. I don’t know what to do I want to continue our family but he can’t stop this has been going on since a little bit before my son was born.