Hi hun,
You were only trying to be a good muma nd inorm your ex about what is going on with your DS. He is the one with an attitude problem. Dont email him back about the stuttering info. I think he is only trying to make you bite at him as it seems like it is a game to him (after hearin the "put your claws away" comment.
I think maybe for your own sanity you need to think of your ex as a joke and anything he says that is biting at you you need to treat as a joke. I would have maybe written back to him "My claws are always out. You should know that by now" or something that makes him think that you are not taking what he says to heart.
I know it would be hard but you will get through this. I hope that you have a good Christmas and that the present swapping for the dummy works. I think that is a great idea!