Don't go tit for tat with him...it will not get you anywhere, but give him reason to keep doing what he is doing plus the attention that he craves. I would keep your distance and not intiate communication with him unless it is about the kids and don't take anymore of his abuse!
Stay above this cad. Remember he left his wife and children so who is he to critisize you. I am personally thinking about dating and really detaching from my W. She is on a dating site and now it begins the 10th week since she left. I think I am fooling myself to think she will be back. She has totally detached herslf. I really think it is time for us to move on. There are people out there who will appreciate what we have to offer.