Sorry to here about your OH , I was DX with Parkinson in June last year and Lewy Body dementia in August this year so bit of a double shock to the system .
I know Alzheimer's and Lewy body are different but the outcome will be the same , I am 58 years old by the way so considered quite young for the dementia side of things.
My OH and myself have talked at length about the future and I've let her know that when the time comes she must do what's best for both of us and even if I don't understand at the time if she needs to put me into care I understand now , and hope that will give her some comfort when it has to happen , as I know it will happen one day.
I don't know of anything that I can write to make you feel any different about your situation other than deep down your OH on some level will know it was the right thing to do at the right time for both of you.
I hope that in some way I have been helpful and I hope things work out in the future.
Take care and live well Cc