I think it is the feeling that everyone else must be having a ball and you feel you are curled up in a ball alone that makes it difficult for some people.
Looking at some of the posts on here, I reckon most people would rather be ALONE at Christmas! That is not to reduce the pain of the OP at all, I am just saying that Christmas can mean great expectations, which rarely live up to the hype at all.
Yes it is nice to have family around, but after an hour or two they mostly snore on the couch, the kids go nuts, the ILs turn into Ogres, the presents were crap and all the rest of it, oh and the clean up will take up most of the next day. Exhausting, and never really lives up to the expectations of everyone either IMV. In truth everyone is glad when it is all over.
I don't give Christmas a second thought. I never watch the ads, I don't buy anything extra (except booze.) That's an essential anaesthetic! I visit family all the time, nothing different about Christmas IMV.
It is so over hyped. It is no wonder people get unwell and depressed, feel lonely at this time. But it is just a day. Commercialism has a lot to answer for.
OP I hope you will be OK. Buy yourself some lovely treats, close the blinds and sleep on the sofa whilst watching something on TV/Netflix/etc. Get drunk as a skunk who cares?
Next day go out to the sales, or for a walk or whatever. Believe me it is all over then.