Kate,
I'm sorry for your stress. What an amazing mother you are though for doing so much--knowing you need to take care of your younger children and keeping your son from finding out where you live and yet spending time with him each week.
The suggestions already given are great. I have one other that might not be an option but it popped into my head. Does your son live on his own? What about having Christmas dinner at his place? I realize it's work for you, but at this point it seems like no matter what you do it will be. Everyone could be invited and maybe he would get into the excitement and responsibility of it. Just a thought.
Sending good energy your way.
Dahti

Dream of the Circle of Women
by Dahti Blanchard
published May 2004 by Spilled Candy Books
visit: www.dahtiblanchard.com