It can't be easy, Godspeed
The only thing I can say which only applies in late stages, it's OK to lie to them.
My friend's mom would always ask "where's Pa", and he would tell her he passed, and she would break down and cry like it was the first time she heard it. Sometimes multiple times a day.
I told him to lie to her, say he'll be back soon or something. Stop breaking her heart. Sure enough, a dementia counselor told him the same thing
Sometimes Iying is the best thing you can do