I personally haven't had to deal with this, but I saw my grandmother get more and more dependent on my aunt and mom. Caretaking really is stressful and to have so much more than that on your plate really has to be beyond stressful. I feel your pain. Please take care of yourself as well. You sound like the rock of your family. I wish you well.

ps- after watching my mom and aunt having to take grandmother to the bathroom, I forewarned my mom that I will do everything I can for her as she gets older, but I will not wipe her!