I know that I have seen cases like this in which the person being mean (your husband) is sort of angry with the person sick for getting sick. Not sure I can explain this fully or well, but I remember being angry with my grandmother when I found out she was terminal, luckily I was not mean to her (well one short instance for which I apologized profusely and which really forced me to understand what I was feeling). You might let him know that more than how you will remember this, will also be how he will remember this. There will be no ability for him to make it up and it will eat at him.
My heart breaks for you, I am lucky enough to have both parents still and cannot imagine the pain when I come to your situation. You are on my mind.