I have no wise words of wisdom, but have been in a similar situation. *I* use to care for partners gma. At that time, she was 101 yrs old. Completely immobile. I was the one who bathed her, put her into her chair, put her on the potty and wiped her bottom, made her food, EVERYTHING. After a year of her care, I had enough, I was wearing thin. She did not have an ounce of respect, not one ounce of appreciation for anything anyone did for her. I took on this responsibility because she was my partners grandmother, because she wanted to remain living in HER HOME, did not want to go to a nursing home.
Finally, when it got to the point that she became physically violent towards me and the $ we were using to bring in outside care for her was completely gone, we asked other family for help. That was a HUGE mistake on our part.
With her dementia in full force, the other family came in, drilled into her head that we 'stole all of her money' and that *I* had been abusing her all the time. They tried to bring criminal charges against me and my partner. Of course, the LEO flat out told them there was NOTHING they could do becuase we did NOTHING wrong.
The other family who were NOWHERE to be found for the 5 years my partner cared for that woman walked in, moved her out of her home and BAM she was gone.
We have no idea where she is, no idea if she is still alive or not. This all happened in the beginning of 2009.
This is not your situation, but I have 100% sympathy with what you are going through. For many months after the other family came in, I was sick with remorse. I was hurt at the lies they made up. I was resentful and angry with gma for saying that my partner and I did these horrible things that were being drilled into her head.
It is horrible to watch a family member deteriorate. I was not even related to gma, yet I loved her as my own. I cared for her as my own. It was a huge slap in the face for others to make accusations that what my partner and I did for her was 'not good enough'.
Sorry, I did not mean to ramble on about what I went through, but guess I did need to get it out. Have not talked about her or what happened since it did happen.
Regardless, Know what you are doing is best. Know that YOU have to take care of YOU before you will ever be any good to her or anyone else who may need you!