Clarity and openness regarding his condition and diagnosis is essential. There is no moral judgement here, he did not choose to have this disease. I am with Beate on this , it is important for people to know and understand that this is the disease which causes him to behave in this way in appropriately and out of character (ie forgetting to visit children and grandchildren) There is no shame, no malice on his part, just the progression of the disease. Your family needs to be part of the change and be with you both as you must handle the situation.
Denial on his part, not being able to face his diagnosis or truly having no self awareness of his condition is sadly all a part of this disease.
My experience, in the beginning of the disease was strange. Initially, I had family members who could not cope with the diagnosis. But thankfully, his family accepted it and our good friends remained close and supportive. The acquaintances or party relationships fell away. I believe that some people were frightened as we were so young, and that got them thinking it could happen to them too. They could not face that, or did not know how to handle that. And they did not wish to see the changes to our lives, it made them uncomfortable.
But our children and my husbands family and our good friends have stayed the course and helped to support us in many ways. Its not over for us yet.................