@solidarity1234,
I'm not sure that there are qualified psychologists that visit these forums.
All that said, it appears to me there are a number of things you are unaware of :
- people don't make decisions for logical reasons, no matter how much it looks like it. Studies have shown there in just about every case, there are underlying emotional reasons, and we pair our logic to match such
In other words - does your father have strong underlying emotional reasons for doing what he is doing?
- as a personal observation, peoples primary traits get stronger as they get older. Cynical people become more cynical, kind people become kinder, bitter people become more bitter, people who love learning continue to learn, etc
So, if you name what your fathers dominant trait has been, you can see if it has contributed to this situation you find your family in.
And if he only has this blind spot in relation to his dying mother, then refusing to think about consequences isn't a mental health issue, but rather, an emotional one.
In relation to his blaming your mother for things, say, not being happy - I don't know how one goes about changing such things in older people. I suspect they can only be lead to it slowly, or with great skill
Personally, in situations like this, many people understimate the power of going to see a counsellor / psychologist themselves - to get advice on how to handle such situations, even while they seek elsewhere (like here).
Please consider it, and best of luck.