Christmas day would have been my Mum’d Birthday too. I think you should make a huge effort not to be alone on Xmas day. It will be a hard one for the majority on this forum however people like you/me have a special sentiment for the time of year. That is why it is important that you make plans, book a Christmas lunch or dinner at a local diner. Walk the highest peak surrounding you, make dinner for an elderly neighbor.
You could contact your local Salvation Army or Homeless societies. Any organisation like that would greatly appreciate your time and effort at this time of year.
I think the feel good factor from helping others might just take the edge off your hurt and it could lead to a positive outcome in the end.
Hope you make some plans and don’t stay at home with your thoughts, take care…