I think Hvert is right...I think if you are able to step back while the daughter is here, she will then have to take some responsibility for her Dad. I'm sorry, I read all the posts, but can't remember if she is the only child? Even so, this should fall more on her shoulders than yours.
Maybe you can try to start treating this as the "job" that it really is. If the daughter is a nurse, she may earn enough money to help with your pay, bringing it more in line with what it is worth! Is there a way to suggest that to her, probably not without feeling badly, but you really need to do it. Drink that bottle of wine first, if necessary
Big hug for you!!!!