Let her do all the talking, and agree as much as possible. Even if she says "You're an idiot". Make her feel in control. Instead of saying "You need to" or "You should", ask her "What if you ----?" and let her believe she was the one who came up with the solution. Never claim the idea was yours in the first place. Win by losing.
It's difficult to stay upbeat and take care of someone who's so negative, my Mom has dementia and she definitely has her angry/depressed moods. Even when she had a healthy mind she wasn't the kind of person people recalled being "soooo nice" she was the one they would say, "your Mom is so spunky." ha.
Anyway, Pamstegma has good advice. I try to re-direct, just like with a toddler. Sometimes it works, sometimes it doesn't. My Mom's therapist says it's important that my Mom feels like she's being heard, so I try to let her vent and complain.
Perhaps part of the problem you have is the same one I have, you hear the negativity and want to fix it, but we can't fix it. That's a really hard thing to come to terms with for those of us wanting to help our loved ones.
My mother was a negative Nancy for years. She could find the worm in every apple. It really was difficult to tolerate the flow of negativity around me. After years of being negative, she has started being nicer. I don't know what to think about that, either. It was easier to set boundaries with a negative person than with a nice one.
Anyway... when my mother was being negative all the time I would listen for a few minutes and then leave. The weight of her negativity was too much for me. I found that walking away was the easiest way to handle things. I didn't want to argue with her or say anything wrong. And I had a lot of things to do, so I didn't want to stop to roll in negativity for too long. Walking away was the easiest answer.
Anyway, Pamstegma has good advice. I try to re-direct, just like with a toddler. Sometimes it works, sometimes it doesn't. My Mom's therapist says it's important that my Mom feels like she's being heard, so I try to let her vent and complain.
Perhaps part of the problem you have is the same one I have, you hear the negativity and want to fix it, but we can't fix it. That's a really hard thing to come to terms with for those of us wanting to help our loved ones.
Anyway... when my mother was being negative all the time I would listen for a few minutes and then leave. The weight of her negativity was too much for me. I found that walking away was the easiest way to handle things. I didn't want to argue with her or say anything wrong. And I had a lot of things to do, so I didn't want to stop to roll in negativity for too long. Walking away was the easiest answer.