I had a mini nervous breakdown last Christmas. DH had died in the summer, I walked into work in November and the Christmas Dec's were up. The shock of the fact that our first Christmas without him was fast approaching (albeit still a way off) took my breathe away. I remember it as a physical feeling.
In the days that followed our leadership were determined to make everything as festive as possible (this was during covid) to cheer everyone up. I struggled on for a bit but went off sick in mid Dec and didn't go back until mid Jan. I'd been coping well until then.
And it's already starting for this year. I don't begrudge anyone a lovely Christmas, but I can't be forced to throw myself into it. It's not that I don't want to, I physically can't.