(((lady))) It's hard hearing the actual words even though we know somewhere that it is a possibility.
Alzheimers, at our age, is normally not an overnight process. Early onset is different - dd older friend's dad was in his 50's. home health is when you know that they can't be alone and literally need to be there for physical help and safety health. It sounds like you and your children are available to be with him. I wouldn't let him drive anymore though - on the property probably but it's a safety for him and for people on the road.
his life will have normality and some tweaks will happen as they do now. it's a shock and takes time to wrap ones mind around it. The changes also surprise us and then a new normal comes. There still is joy.
All in all - it is so hard - I am so sorry you were hit so hard with all this information. His headaches and memory loss time adds to the struggles he has - I feel for him and for you all! I wish I could take that away from him; I really do!
I have had Alzheimers in my family 4 times - it's all been gradual. New normals ebb and flow and it took time to get to each of them. I am sorry!
my heart is with you and him and your family! so much love to you!