It's not over just because you're not going to H's house for Christmas this year. It's over when the fat lady sings.
I'm really tired so I can't remember off the top of my head - do you feel control was an issue during your M with h? I'm wondering, my H said something similar when he left.
A vet could help you with the email better than I could. It sounds too wish washy for me, personally. It felt like you were giving him every opportunity to shut you down after The Christmas Eve part. (I'm not trying to be rude, I really am not.)
Me, (and take this with a grain of salt because I'm still new, and my H says I was controlling) I'd say something along the lines of:
Hi H,
I am in agreement with you taking the kids for Christmas Eve - I know how important Christmas Eve is in your family and maintaining traditions. The kids would enjoy having you here on Christmas morning, we will probably start around 8. You're more than welcome to come by. S4 wanted to get you a gift, so we went shopping and it's here at the house. Please let me know your thoughts so I can plan accordingly.
Again, I'd phone in a vet, cause like I said, I'm not good at this.
As for the decorations relating to your H's actions, who knows? He may just be asserting his self and finding control and doing what he wants to do. Your BD was so close to Thanksgiving that he may not have wanted to rock the boat, but now as time has passed he may feel differently.
Good luck!
M:32,H 32 T:10, M5 BD/H Move Out: 9/2014 - extreme anger H Mental Illness Diagnosis: 4/15 Served D Papers: 10/15 Divorced: 11/15