You've done amazingly!!! You should be verry proud of yourself and I think you're doing the right thing with your son too. Telling him he will never see him again can be scary for a little one, "yet" is a great idea because eventually he'll just forget.
I too would be worried about the sheer number of calls and texts. This is definitely a man who is used to getting his own way. I believe he will step it up a notch before he gives in. Be careful and stay safe. x