Am shocked you tell OP this.
OP, your story is nearly mine.
My DD was diagnosed with brain cancer at age 29; she had three small children of her own, 9 months, 2 yrs, 4 yrs old at the time. Her father and I divorced when she was 4; I remarried when she was 9.
When DD was 10, we had a son, when she was 12 we had a daughter, and then another son when she was 17 when she was in the second semester of her in her freshman year in college - she was age 17 (she went to college early as she skipped her 9th year in high school). My first child and last child are 17 years apart.
I was managing my children, her three half siblings when she was diagnosed; all three were living at home or just beginning college, etc. My spouse worked all over the world, so he was not home to help a great deal with raising the family and taking care of everything, it was almost as if I were a single parent; he was home, but usually only about 5-6 days a month.
My daughter when through two brain surgerys 6 years apart as her brain cancer grows back ever so often and surgery is done whenever it causes issues. I did the best I could to help her endure her cancer, and she lives with it every day the last 16 years.
Never once has she called me on the carpet, complaining about this or that that I didn't do, or express the negative, guilt inducing things your daughter is doing. Am sorry to say this but your daughter seems to want you to feel guilty or is she immature; she is 40 and she does need to grow up; her expectations are out of wack.
In fact, one time my broke down into tears and apologized to ME that she "had gotten brain cancer" and "made MY life upside down". MY life?? She was more concerned for me having to juggle my kids and hers now and then to help out.
And yes, it drove me crazy being in her home, too, just like you! Each time I left after visiting more than a couple days at a time, I would breathe a sign of relief to get back to my less chaotic life.
Your daughter is 40. She has a therapist. You have done what you can, with what energy you have at this time of your life. You are fine, a good mother, obviously, with a lot on your plate - the autistic son is a huge responsibility. I am sorry your daughter has breast cancer - having a child with cancer, no matter what their age, is so difficult - we worry we will lose them and that too causes stress we try not to show.
I hope your health problems stabilize and please give yourself a break.
Your daughter nor anyone has the right to give you a hard time when they have never lived your life. Your daughter needs to be happy she still has you in her life and listen to her when you have the energy.