Norm and Michael,
It is a very hard decision to make and a huge adjustment. I knew my Dad wouldn't budge on the issue until forced to and it took a incident with her getting lost, falling and then going into assessment and being told he needed three full time caregivers for him to agree to put her in a NH.
He visits her every other day, I take the other days. Mom hasn't forgotten who he is since going into the home. She still knows me also which is nothing short of a miracle. Hospice also helps in her care and she is watched over 24/7. The NH personnel love her and she has many activities throughout the day. At home, we couldn't get her off of the couch.
I can honestly tell you that it has been the very best thing for all of us. Especially Mom. I still feel guilty but I know I couldn't take care of her ( bad neck and back) and she is content.
I don't know that once they are in the final stage of Alzheimer's you can ask for more than safe, warm, fed, and as content as is possible.
You need peace and you might just find it if their basic needs are met and your time with them is spent in just being together.
Take care