Whether or not she is a good person is almost moot. She has not treated you or the boys well, and yes, she has been very manipulative and deflects all responsibility for any issues between you onto you.

You get all the blame, despite all your efforts to help her, to appease her, to be there for her, to support her, and to do more than your fair share of the household duties. That had gone on for years, but I think you maybe excused or explained away her behaviors because of her physical ailments and down position in life.

And now, your boys don't want to be in her presence. They see her manipulations and poor treatment of you AND them. They see that she is toxic and they stand by their father.

And, you, with a heart of gold, have been SO understanding of her and have tried SO hard to get through to her, all these years.

Is she a bad person? Well, she is certainly very toxic to the family. And she has caused harm. Whether that is deliberate and consciously malicious or not, it's hard to know, but that should really say it all and is all you really need to know.