Wow, 7 weeks after leaving you he is married to someone else? That takes twattery to a new level!
I do wonder whether he has been railroaded into this wedding and that he was showing some "buyers remorse" at the wedding. But if he was miserable yet still married her, that shows what a weak man he is.
If he is allowing her to abuse you, lets her bully him into not seeing his son and lets her think she has the right to ban you from contacting him (er..hello, she is his wife, not yours!) then is that really a man you want?
Really?
You are seeing the real him now, the man you thought you were marrying doesnt exist, he never did. This is the real man, someone who will abandon his son in order to keep his screaming harpy quiet. She sounds vile, utterly vile, but she isnt your problem. Contact the CSA to make sure you get what you are due to help take care of your son, and I agree that counselling would be a very good idea. You have been through a very traumatic time and it will take a while to get over that, and counselling can help.
If its any consolation, I give it a year before he is bonking someone else, but PLEASE dont let that someone else be you.