How do I survive an abusive mother (88) who is healthier than I am?

I was raised with parents who were verbally abusive, non supportive, loving or nurturing. My father had serious violent rage issues and was a functioning alcoholic. He passed away in 1999. My mother now 88 is clinically insane. She lives in another state and still manages to abuse, criticize, degrade, accuse and make me feel guilty for all her problems. Her only health issue is age. I am visually impaired, have diabetes and severe refractory asthma. Her estate will go bankrupt when she dies. I am estranged from my brother who is executor of her will and doesn't pay his own bills let alone hers. She has taken me totally out of her will, however her problems always seem to land in my and my husband's lap. We have spent more money on her over the years than my brother has even thought about. It is dangerous for me to be around her. Usually after we visit her I get sick and end up back in the hospital. She baits me and we have terrible fights. She has told me I don't matter, only her son does. I have two grown daughters with families whom she has managed to gain favor of over me. This started right from the cradle. I tried many times to end it with my parents and didn't as my husband lost his parents at a young age and I wanted my girls to have grandparents. I was born 2 1/2 months early in 1952 at 2 lbs 10 ounces. I am partially blind. My mother did not error on the side of caution and stay in bed. She could not handle a child who was not perfect. I am in therapy trying to learn self care and deal with my family. I have started to set boundaries with my mother and now she has ensured that most of her family no longer talk to me. My daughters also favor her. When we visit her I buy her anything she wants. Afterwards she tells me all the flaws in what I bought or repairs in her home my husband has done at our cost. I am afraid of the mess and danger to my health when she dies. I don't know what the rest of the family will do to me at her funeral or even if she has money to pay for her funeral. She still has a mortgage on her home and a leased car. If I don't attend I am afraid my two daughters will never forgive me. I also don't know what kind of trouble my brother will cause for me regarding her estate and money which she doesn't have. Nor does he. He is executor and I don't feel handling any of her estate is my problem. This woman may outlive me. She never asks about my health, my eyes, diabetes or asthma or if I have been hospitalized recently. Right now my husband does not want me to be alone with her as that is when she goes after me. She lies to my children and makes up her own reality. My children do not want to know anything about my childhood or the abuse I've suffered and still do by her. They think Grandma is just an elderly women who gets nasty due to her age and I should look the other way. I do not know how to handle this woman anymore. To me she is not my mother who happens to be elderly, but an elderly woman who happens to be my mother. Any advise from anyone in similar situations?