What a great topic. I just wish I had some great advice. I haven't had to deal with this yet and I can only imagine how drained you must be. Are there any siblings that can help you take care of the folks? Are they eligible for any type of care taker?
Also, this is going to sound like it's coming out of nowhere... but have you heard of Dream Dinners? I know they are nationwide but I'm not sure if they are in your area or not. I'm addicted. You can make good, healthy pre-prepared meals at the stores, freeze them and then basically pop them in the oven/stove for dinner and they require very little preparation. This might be good for your folks (you can stock up) and for your family when you're in a bind. Just a total random thought and idea that might make your life just a little easier!
Good Luck!

Also, you might want to join the "Family Issues" community and post something there. There's bound to be more people in your position.