Martha,
I just read your update as well. You and your mom are in my thoughts and prayers. I know its hard but do what you need to do for yourself. If you need to fall aprt do it, maybe one of them will step in. And try not to (easier said than done) to let their non coping become a burden on you. Dont babysit them. Let them work through it on their own.
You mom is very lucky to have you