Oh wow, you're in my age group....I will be 66 in August. I know exactly how you feel. Just when we think we can sit back and enjoy life...boom...it throws you a curve ball.
I haven't read your past posts, but I take it your husband has colon cancer? We have a good friend who went through much the same thing a few years back. It was a long recovery, but he is doing so much better these days. He did go through the chemo though. He had a colostomy for awhile and did not cope very well with it, but when he had it reversed things became much better. He has gained back quite a bit of his lost weight too.
As for the grandson moving in with you. Just think, this too shall pass...lol. When our daughter was going through a rough divorce eight years ago, we practically raised our two grandkids (aged 6 and 3 at the time) for two years, until she got her feet on the ground and met a wonderful man who treats our grandkids like his own (he has no children of his own). Unfortunately, all the stress contributed greatly to my UP (proctitis) and I eventually needed surgery, but glad I had it.
I wish you and your hubby the best. Keep us updated. If he is not happy with the surgeon, could he seek out another opinion? I refused to go to a surgeon here in south Jersey and went to Philly for my operation.