Both my parents were pretty nasty to me throughout my life. Now my mother is housebound her nastiness is more pronounced as her world has become so much smaller. She has been so nasty to friends that most/all have dropped her, so she is stuck with me and DB (on occasion). And I think that pains her most to be reliant on me, who is clearly doing what I am doing for her out of obligation.
If I was a better person, I would do the things that I see others doing with their elderly parents, like take her to a garden centre, or shopping, etc, but I don't have the time nor energy. Or frankly think that she deserves that level of input from me.
I find her racism hard to take. If when I take her to a medical appointment I dread what she might say if the medic is anything other than white British. She thinks she is being clever, or 'has rights' to say things - 'I can't understand what they are saying, does nobody here speak English?'. Once is bad enough, but the dementia means she will then say it 20 fucking times in a row, with me apologising each time (she's deaf but refuses to acknowledge it or do anything about it, so anything other than shouting tends to mean she can't hear.
Last GP was black, and had my mum turning to me and saying 'I can't understand him, where is he from?'. And me saying 'LONDON'. She then said, 'you think you are so clever don't you'.
I'm not cruel (I don't think?), but functional and pragmatic.
You reap what you sew.