Boy do I know how you feel ;( It was all I could do to put up the tree this year, but I did. I haven't been able to bring myself to buy my AS anything yet either, I know I will though..just basics that can't be sold for drugs if he goes off on another bender. I also ask God every single morning to help me to 'let go' and stay out of his way...beginning to accept that my way isn't the way of my AS's HP too.
I also repeat the Serenity Prayer several times a day when I feel myself falling into the trap of dispair, I also pull on support I've gotten here where I've learned that I do deserve happiness in my life, and the only way that is going to happen for me is to remind myself that I am not my AS...I too only have so much time here in this life and I'm going to make the best of it dang it!
I think it's a great idea for you to go to your sisters for Christmas...it does us mom's a world of good to spend time around the normal people in our lives, helps to remind us that life doesn't have to be full of the 'drug drama', we have choices too..
You didn't cause this, you can't cure it, and you can't control it....true true words...