He’s likely to be tired as hell and miserable, particularly if he was any kind of athlete or had hoped that one day he might be able to convince your Mom to get back together. So he’s probably not enjoying being weak and useless one little bit.

Try to cheer him up if he gives you the chance, when you can. Steer away from anything sensitive like relations (you’ll have to ask Mom, not me) and don’t let it run your life.

Your Mom might need physical help or cheering up as well. Having an invalid around the house is not all that exciting.

Depending on your age, you might be able to do something there as well.

If the situation bugs you then go for a walk or a meal with your Mom and talk, don’t keep it inside. Open up and it’ll get better. She might appreciate the break.

However, there are plenty of things that could go wrong with a colon. Here’s a list of some of them. A little fun reading for you…
http://en.wikipedia.org/wiki/Colon_(anatomy)#Pathology