in my experience, it seems they feel that any attention is better than no attention... If they can get a response out of you for anything, at least it's a response.
When my birds are screaming at me from the other room because they want attention, I can't go in there, no matter what. Even if I were to go in and scream at them to shut up (negative reaction), all they see it as is a reaction, an ackowledgement. "I scream and she comes in... no matter what happens after she comes in, I scream and she comes in" Its a very juvenille tactic... like a kid throwing a tantrum to get what they want. As long as they see they are getting to you in any way, they will continue to do it. And the more you respond, the worse it will get, and the longer it will take for it to stop.
Keep up the good work of no contact. Don't let him get to you, no matter what he says. None of it is true, you aren't rude, or any other names that he calls you. You are moving on, and it scares him to death, so he is grasping at straws.