Joan, I agree with all that GramE said so well. You are the one supporting everyone in the family. But still, relatives, especially older ones, need to respect your boundaries. Being old or upset doesn't give her the right to treat you that way. If it helps, I've heard that people get meaner as they get old, because their brains shrink or dry out, or something! Dementia patients can get really angry.
It's sad to see, but I had a very sweet student in my Silver Sneakers class who was advancing in dementia over the years. I saw her transition from a lovely person to someone who was alway angry and ready to lash out. Finally her son recognized she wasn't fit to live alone anymore, and brought her to live in his home... so she's not my problem anymore! It's definitely an aging brain thing.
Quilt Addict, I'm thinking 'fiddlehead ferns' when I look at your fabric...