Your h will not forget the many wonderful and happy memories that he has made w/you and your girls. Keep in mind, even if he were to get Alzheimers, they remember things of the past and tend to forget what the present day holds for them. They regress to children in many ways. Did you see the movie about Benjamin Buttons? This movie reminds me a lot of what the MLCer goes through a bit.
You do realize that your h is very jealous and resentful of what his daughters have accomplished thus far in life? Of course, he's going to put down anyone that is successful and doing great right now, because he's not getting the attention and being put on a pedestal for what he's accomplished.
Actually the negativity towards your D25 is not unusual. They tend to gravitate towards one child more than the other. Is he closer to your other daughter? He's projecting on to her how he feels about himself.
I can understand how your daughters would be confused about his behavior. Maybe you need to share some of the books that you may have read about MLC w/them. It would help them better understand some of his behavior. Jed Diamond's books are great and they may help as well.
Enjoy your day! Maybe you'll get lucky the Easter Bunny will come along and drop a few eggs on his head! LOL!
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.