I think he is still in shock over his diagnosis. He needs a lot of time and patience. Do your best to keep the kids occupied and let him have this time to process all that is happening to him. He most likely has post traumatic stress which is very common for anyone with his dx. Try and get him outside if the weather is nice. Green surroundings help with depression and stress. Talk to his Dr's about this as they can help you too by involving social workers etc.
Make sure you call upon people to help you get time away from everything too. Get some time just for yourself. And pamper and relax. You need this to re charge.
He needs space too. Ask him what he thinks he needs, it might take a while for him to come up with anything. If you have faith then call upon your pastor to come and talk to him.. Can you call any friends of his..He might be forced then to clean up and pull himself together.
I can tell you I laid in bed for almost 11 months during my treatment. I had all of the above. Its brutal and awful and its the same for you too. Try your best to get someone to take the kids as much as possible so they don't see him suffer and it gives you a break.
Hang in there its one of the most difficult times in your life. Try and stay in the moment and not think to far ahead.