You are not alone in this situation. I am almost 57 years old. I had to make the decision to no longer communicate with my mother about six years ago. My daughters are both grown and I have grandchildren. One of my daughters saw my mother a few months ago and said she thought she was in bad health. So, I called her and she came over and visited. My health problems are much more serious than hers. It didn't take long for her to start calling and driving me crazy again and for that mean person to come out again. I called her night before last and told her we had to go back to no communication because I could not handle her insanity.
She was never a mother to me because she was always drunk. She was never a grandmother to my daughters. She even had a third chance with great-grandchildren and of course, she's blown that too.
I know some people think that just because she's your mother, you have to try to have a relationship with her, don't let that bother you. There are some situations that those people have not had to live through, so do not let anyone put a guilt trip on you.