I remember your other threads.
Op is paying thousands for bils care.
He is by all accounts a total nightmare and was one pre brain injury too.
Alcohol was a key factor iirc
While its easy to say " ohhh its not his fault" the lived reality is much harder. I certainly would be at my limit with it but be struggling because of my dh.
Ideally Dh needs to go early to collect him and have some kind of Mexican stand off and get him to wash but it probably wont happen. Ideally with some carers , although iirc he doesnt have carers.
Re your parents and father I dont understand this conversation flow but you clearly dont like / love your parents.
me: Dh and I are thinking of spending next xmas in UK
Df: its too cold. I wont go.
Me: thats fine. I wasnt talking about you. I was talking about my plans.
If it is the same poster tale my advice....
In jan/ Feb time find an "amazing deal" and book a long haul winter break. When you find the dream holidayvthe price over xmas 26 will be "very good"
Be it ... Skiing, the beach, the Amazon jungle pick something...
Bil and his dd can spend it together, your parents have each other. It's one year etc...apart from once you break the cycle do it every year
Separately id start couples therapy electrically to have a space to navigate your bil.