Bettyanne, that is wonderful news about your husband. Whew! So hope he continues right up to a lasting remission. If it's prostate cancer, that's surely possible.
How horrible it must've been to have a grandmother who screamed and yelled all day in the household where your helpless brother lived. And you, being neglected so terribly by that broken mother. I'm so sorry childhood was like that.
I think people recover from those kinds of childhoods in varying degrees and at various points in life: never too late! And the fact that you take loving care of your family and have steered your own ship in the absolute opposite direction from your mother's personality disorder and the rest of the dysfunction is truly admirable.
Since you feel haunted still, though (and understandably), and ask for advice -- my best advice is to seek out a wise, compassionate therapist and unpack the whole damn thing. That means going once a week for a good long time. (Think a year, not a month.)
It also would mean caring enough about your self, your happier old age, your serenity, your sense of purpose and hope...to say to yourself: At 76 (or 86), I, Bettyanne, deserve to learn and heal from lifelong wounds I never before have had the time or ability to take care of. I am as deserving of that care and healing as any other human being who walks.
If there are obstacles to finding and accessing a good therapist, determination is what you'll need. Just decide you are deserving and go for it. There are sliding-cale options in almost every location except extremely isolated rural towns these days. And even in those situations, some people benefit a great deal from "tele-therapy" they access online (live video conversations with a therapist).
If there is a Board for the Aging or any sort of services for the elderly organization where you live, make an appointment and go in to talk to their advisor about how to access therapy. Never abandon yourself or decide you are not worth it. You are.
I have known quite a few people who entered therapy in their 70s and were so profoundly glad they did.
Hugs
Hops