Confused on what to do.....

Quiana

So I have been dating this man for 3 months known him for almost 2 years as friend the relationship just sorta formed on its own. I have falling for him in such a short time. Everything is basically great my son loves him and he's good with him. They hangout and get along. With me he is affectionate , loving , attentive , caring , giving and make sure we are always good. The only issue we are having is he has a 3 year old daughter with a woman who is not ready to let him go when we first started dating she never called bc she was dating someone else now she calls him one day a little over a month ago and he doesn't answer the phone all the time bc him and I are always together when we are not at work so she asked him why he don't answer the phone and he was like I'm dating someone else that was all he had to say know she calls him back to back to back I mean at least 25 to 35 times a day about she loves him wants him. Can she sorry even texting and throwing her Colchis through text and he is getting annoyed and I am definitely annoyed. He told her it's over but if the baby needs anything he is always there. He wants to change his number but there's a baby involved and I have never been through baby momma drama before I love him and trying to stick in it with him ,how do I handle this? I need advice?