Big fat hugs, Florence.
I don't know what to tell you because I've never had to sit alone at Christmas, which is probably the only holiday that really mattered to me. I've spent Thanksgiving and New Years alone many times, but somehow, that's been OK. I think because I've been able to tell myself that "it's not that my children don't
want to be here; it's that they're court-ordered to be with their dad."
I didn't try to do a holiday celebration on my own; that would probably have been sad. I just did something completely different instead. Thanksgiving one year I went for a long hike and packed food and hot coco. (Luckily I had my phone since the kids called and said they were at a party and AXH was drunk as a skunk and intended to drive them home...). New Years I spent alone... I think four years in a row? I've made it a habit to buy a ridiculous amount of sushi and candles and sit and read favorite books by candlelight and eat sushi and drink green tea.
For me, doing something that
I really liked and wanted on those days helped. I know that "going and helping at the soup kitchen" is the advice you normally get, but frankly, the person in most need of my help and support has been me. And that's OK.
For me, NOT trying to make it a pale version of a dream holiday worked. And I'd think "Oh the day will come when I can cook a turkey larger than a smart car and have fifteen people at the table -- today is not that day and that's OK."
I don't know if any of that helps, but that's how I've handled it.