It is not easy to take care of someone with Alzheimer's disease. People who take care of Alzheimer patients are susceptible to become depressive. Did you offered him some concrete help?

I know how he feels. No one likes to have to put thier loved one in a care facility. He has to realize that Alzheimer's (depending what stage they are in) can even be a threat to the person trying to take care of them. The third stage is a very combative stage. They do not know what they are doing or whom they are doing it to. Simialar to a paranoia (severe). You could be indagering yourselves. At that point, normally a facility will put them in a locked unit so no harm will come to others there, and they will be highly medicated.
Speaking as one who has worked in the area, please reconsider this before making a large mistake. The will come a time where she will have to be watched 24/7 and you will have no choice be to put her back in facility care anyway.

Just looking out for your safety.