So sorry to hear man. :(
I am no expert nor do I have personal experience with Colon Cancer but (going through what I am going through my dad's lung cancer which some day I may post about) maybe I can offer some advice. Should they go for an aggressive treatment of chemo/radiation, be proactive during the chemo--in other words be ready for any side effect--some meds cause severe constipation, while others case really bad diarrhea. Fill all meds they suggest--it is better to have it and not need it. I don't know your financial situation, but do not be too proud to take any grants or assistance that you qualify for. A lot of them start around 400-500% of the poverty level--so you can make some substantial money and still qualify. My dad's meds are $1,550 out of pocket every 3 weeks and then they do a Neulasta shot to build his white blood cells--this shot before insurance costs (are you sitting down?) $10k--my dad's out of pocket on it is 1k every 3 weeks. There are 3 companies helping him and my mom out to pay for these and we are covering the rest, but there are many out there to help. I am not sure if your job offers FMLA, but if you can access that or take a leave of absence, that's what I would shoot for. Like others have suggested, she is going to need you to wait on her hand and foot in the beginning. Your kids are so young, so they are not going to understand why mom is so tired, so any help you can get there will make your life easier. If you don't have a Netflix account, get one so movies with mom and the kids will be a way for them to spend time together and she can still rest. Diet is important. Protein seems to really help the body regenerate after chemo.. Turkey is a big help.
The good news just reading about this stage is it seems to have a very good prognosis. So just stay as positive as you can. If I can be of any other help, please feel free to PM me.