yikes. I can't believe he said fine. But whatever. This would be a great time to enforce the no call backs until after 2 messages and 24 hours have passed. It might be a good idea to send all him future emails to a junk folder... you can always read them later but at least you don't have to respond immediately.
I follow these boundaries because the less contact I have with my ex, the better. Otherwise I just feel sorry for him and end up feeling guilted and manipulated into doing things I don't want to do. The less contact I have, the less energy I have to spend on my ex, and the more I can spend on my child.