I believe that how you think and feel is very UNselfish... and for that you should be proud of yourself, not feel bad about yourself. You are putting your mother's needs and wants ahead of your own.

You could have said-- "I don't care if she suffers, as long as she is still here with me for as long as possible, until I AM ready to let her go". -- You see?? how thinking this way is awful and thinking the way you do is loving and compassionate and so unselfish.

its a difficult time and confusing-- please be kind to yourself

fins