My thoughts are with you.
I, myself, find it very hard to deal with Christmas this year. This is the first year without my Father, and Grandmother. My Dad died in January and my Grandmother a week after he died. I know it's hard for all in our family, but especially for my Mom. She will have it the hardest. I was so glad that I got to spend it with her. I love her dearly, and can't imagine the pain she must feel on a daily basis.
Keep your chin up, and take solace knowing she'd in a much better place, cherish your memories.