Have you talked to your boyfriend about this? I would want to know if his father has always been this way (obnoxious, demanding and unable to care about others) or if this is recent behavior. If it is recent behavior, I would be considering some sort of dementia.

Either way, he is not going to get better. If I were you, I'd minimize the amount of time I spend with the father. The other thing I would do would be to say, "Not in my house" when he does things that you don't like in your home.

Ex.: "Your wife isn't stupid and we don't talk hatefully in my house."

A lot of the other stuff, like her waiting on him hand and foot, I'd ignore.

When she complains to you, you can calmly tell her, "You've chosen to do this." She'll likely say, "Oh, but he gets worse if I don't...[whatever it is he is demanding] to which I would reply, "It still a choice."

Many people, especially people who have been beaten down over time, stop realizing they have choices. You're not judging her when you say that, you are stating the obvious which may not be obvious to her. I hope this helps.