I am so sad to know she is in pain and complains all day. Shes says I did for you, now just do it. This is going on for 15 yrs. She excuse sister of stealing, talks how much she hates her. It is all so sad. My life is over. I am very sad and I love her. I wanted to go away, she said no.
She is not dealing with it well.
She complains constantly.
She resents it when you find aspects of helping her difficult.
She is angry with your sister, because she believes that your sister stole from her.
She gives you a hard time but insists that you stick around to help her.
This situation has been developing over 15 years. So, since your mother was 72, which is actually not that old.
Why do you say that your life is over? Or do you mean that this is a feeling that your mother expresses?
On more practical points:
What are your mother's care needs?
What is causing her pain?
Where is your mother living?
Does she live alone, or do you live with her?