K.H.
I am so sorry for your situation. My mother has cancer (doing well, but not in remission), my mother-in-law passed away from cancer, and my husband also has had cancer (in remission for 6 years). We have been there for each other.
It is hard to be supportive of a man whose loved one has cancer. I know some people say their husbands become very withdrawn or in denial. I am fortunate to have a husband who will talk and not bottle it all up. I would encourage you to be patient with him and let him set the pace. I would imagine he will be more grouchy than usual and may snap at you or the kids--expect it. He may not respond to all the 'girly' ways we cope- cards, long talks, etc. I know some men seem to want sex at times when perhaps the wife is thinking, 'how can you be thinking of that at a time like this?', but it can be a stress reliever and a distraction from their reality.
I don't know that i would tell the children anything more than 'grandma is sick' and I don't think I would do it unless it is obvious she is sick. I don't believe in keeping kids in the dark, but the concept of cancer is above a 4 year old's head.
May God be with you. I certainly believe in the power of prayer and wish healing on your family.