NeedMore, that sounds grim, but at least you know the carer knew the truth. Your reference to the weakening of constraints echoes what I see in my mother.
I had a grim visit to her today. She started complaining virtually as soon as I came through the door, and was determined to find an excuse to moan and be contrary about everything. She's developed a problem with her ears (they probably need syringing) and I told her that I'd arranged to take her to the GP's, but she was talking over me about how she didn't care, it was all pointless, and she just wanted to be dead. But she then started complaining about her ears and was quite disconcerted when I pointed out that I'd just told her I'd make arrangements to sort that out.
She seems to get herself into a groove where the same phrases come out over and over again and she won't listen to anything so there's no point in sympathising. As I've said, I realise her life is very boring and she has reason to be depressed, but what is so difficult is that she categorically refuses to try anything at all which might help
Today I tried the robust approach, suggesting that carrying on like this wasn't helping her and maybe she should try putting that energy into doing something constructive, but it was as if she resented any suggestion that might help her. She was saying that my dad would be horrified if he saw what her life is like now, and I had to bite my tongue not to point out that, on the contrary, what he would be horrified by is the way she behaves. It all gets mixed in with stuff about how kind I am but how it's too much of a burden on me; but it really wouldn't be any sort of burden if she would just cut down the moaning.
I suppose one of the thing that really gets to me is that, a few years ago, she was always very intolerant of anyone with anything like depression and would loudly proclaim that they should just pull themselves together. I worry I'm getting like that with her, but I don't really know what I can do when she just won't allow anyone to try to help, or make any effort to help herself.