That seems to be his problem not yours, even though you have a nine year old son together and it's important that he feels mom and dad get along ok, it's important for you having moved on and having a new baby i'm assuming with someone else, it's important that you set some rules!
Like he should not call you unless it's life or death or pertaining to your son, you have to make it really clear that you don't want to know anything about his personal life because you have your own life to live and you are happy where you are. You need to tell him to leave you alone with those things, you will not leave and move in with him under any curcumstances so it's no point in even asking.
And make it cyrstal clear that his and your relationship is over! My ex has done this he hasn't found anyone since we've broken up two years ago and he seems to want me back at times, i've moved on with someone else and after repeted calls and abuse that I look at it as I had to tell him that I would not ever go back to him and was very very happy where I was and with who I was.
You will need to keep him part of your life unfourtnatly since you have a child together but thats it!!!! You two are no longer together and that's not going to change and he needs to accept that and any problems or fights he has with his current women are not your problem nor do you need to know about it,
if he has problems being alone then make it clear that it's his problem and not yours!
I hope everything works out for you, after all you have two beautiful children now to to take care of you can't baby him too, remembe you have two kids not three.
Take care
