Why do people invite ex husbands to Christmas dinner?

[Verysad1978]

I saw this on another thread. And I am honestly not being provocative but why do people invite ex husbands to Christmas dinner etc? I am in same house wIth separated partner. I can’t wait for this just to be over. And move on.
I can’t imagine inviting him to dinner next Christmas. But people do it. Is it the right thing to do? Why?
I suppose I’ve a year to get my head around it

The very thought of both my ex husbands staring at me over xmas dinner makes me feel nauseous.

When we’d first separated, I invited him because all the children were coming to mine and it seemed kind as otherwise, he’d have been on his own. That lasted three years. It is unlikely to happen again, because the children wouldn’t want him there now, but we are on friendly terms, in general.