You have my deepest sympathy, aligncare. That's a very, very hard path to walk.
It doesn't matter how much you know intellectually that it's going to happen, or how great a blessing you know it will be for them, when the terrible day comes we're suddenly five years old again and our mommies are leaving us.
The only thing that made it bearable for me was my absolute certainty that my mom was going straight to heaven and that I'd see her again some day.
Thank you for the kind words. Alzheimer is devistating. And society will have to brace itself for waves of boomers soon getting sick this way.