I'm going to hold my aunt responsible for my mothers death
Why are you holding your aunt responsible for your mother's death?
My aunt was not available to help my mother when she was sick
You do not know the nature of your mom's illness since you are not a doctor. Chances are, there was nothing that your aunt could do for the situation. If you felt that your mom needed help, then you should have been available to help her.
She was diabetic and only had one leg and needed the help that my aunt could have provided. I want to hound my aunt for the rest of her life.
I am sorry for your loss but it is not your aunt's responsibility to take care of your mother. You shouldn't blame her for not doing more, maybe she couldn't.