Even though for me this is just a cultural holiday I wouldn’t want to be alone on Christmas Day. This sounds so phony but if I was you I would check out local churches that have special Christmas dinners for poor or homeless folks. It would give you something to do. You wouldn’t be alone. And you would feel grateful about your state in life compared to many others. Also - sorry about your dog. I’ve been through it several times and it was more crushing than the death of any human for me.