Am i being over dramatic?

Ok so i have been in a relationship 4 years we have a 1 year old. When i was about 3 months pregnant my boyfriends "friend" (girl he used to like) would come around to visit him late at night for an hour or 2 they would sit outside in her car. We got in arguments untill i told her off she didn't come by anymore. When i was around 6 months an old friend decided to text him late at night i answered and she decided to get into an argument with me saying i had no right to say anything i was just carrying his child. We seperated for a few days, he didn't defend me or stop talkong to her. Now that our son is 1 i came out of state to take care of my disabled mother for a while and recently found out he has herpes (i got checked and im clear) & he is now talking to a girl on fb.. He left his account logged in on our tablet so i saw the messages... I confronted him all he said was he is sorry for making me mad. I said i no longer want to be with him... But he keeps asking for another chance and we have a son together i just hope im making the right choice.