I am sorry to hear about the shocking news you received about your little one. from your last post, it sounds like you two have some good plans in place.
my aunt has downs. she lives independently, works, has friends and more hobbies than I do! she lives a more productive life than most people. she has always remained particularly close to her parents. when my grandfather passed away, she became a very significant source of strength and companionship for my grandmother--whereas the other kids in the family had moved away.
I can imagine it is nice to hear these stories, but doesn't take away from the concern and fear you have. i know for me, the decision would be exceptionally hard. and unless i was in your situation, i couldn't tell you what i would do.