princessbelle,
I am so sorry. I did not know that your brother passed away.
My father passed away this Spring and my maternal grandmother a couple of months ago.
It is going to be a tough Christmas.
My sister will not be in town this year, so it will just be me and mom. We have decided to change things up and she will come stay here at my house Xmas eve and then we will both go to my gf's for Christmas in the morning.
This way we will be doing nothing like we typically do every year. I don't want to see his empty place at the breakfast table on Christmas morning, and I don't want to notice the lack of ever present video camera in my face. I think this will help. You really might want to change some things up.
She does not want a tree and this is ok. It sounds like you guys made a good decision in putting up the tree, so that your mom had the option to decorate.
Hang in there. Know you can PM me if you want to talk.