I wish I had an easy answer for you, but I don't. I just really feel for the situation you are in. This is a horrible disease that affects everybody involved. I lost my mother this past january. My kids were very close to their grandma. I had to leave home and move in with her to care for her. They would visit grandma and I everyday. They watched the disease from start to finish. It was not easy for any of us. My kids are a little older 9 and 5, but it was a bad situation no matter what age.
My only advice is to surround yourself with family and friends. Seek counseling for all of you. Know that you are not alone. You will have to find a way for yourself to heal and be there for your children. No that your husband will eventually be free from all of the suffering. I wish you strength and love. Take care of yourself.