My mom had a stroke July 2016 and my sister lives with her and is her primary caregiver. Although she is recovering very well physically, she still cannot fully utilize her left hand and she has difficulty remembering to pay attention to her left side. She often times gets angry with my sister and says very hurt full things to her. When I (her other daughter) picks her up to take her to the gym for exercise, she dumps on me with a lot of negative things about my sister. How should I respond?
Just redirect her as much as you can. Don't engage in a conversation where your mom is being critical about your sister. The main caregiver often gets the brunt of the dissatisfaction from an elderly parent. If you and your sister switched roles your mom would probably being saying the same things about you to your sister.
I'm sorry you have to hear your mom being negative about your sister. I'm sure your sister is under a lot of stress from caring for her daily. Because your mom is so negative, have you asked her about moving out? Will she consider assisted living? A nursing home? Or hiring a caregiver?
My dad was also very negative after his stroke. I feel there was some brain damage after the stroke and maybe this affected his personality. They also say depression is also very common after stroke. I know its not easy on your mom. Maybe she might benefit from going to a seniors centre during the day and getting more company.
And for yourself I would consider talking with a family therapist or counsellor. I know you are doing your best too, but hearing all this negative talk can wear anyone down.