Hi Wendy, welcome. Nelie has made good points and I want to stress that the treatments affect some worse than others. He might do quite well and get through easier than some. Try not to freak out It won't help. Take each item one at a time and you will get through. I personally don't think you will have to alter your lives too much if at all I think it is good that he stay with you for the treatment time for the support.
While I don't think you have 3 heads, letting this cancer run it's course without treatment is not a good option. If he is otherwise pretty healthy he could have another 10 years (or more)

Take care and come back for answers!

Mark, 21 Year survivor, SCC right tonsil, 3 nodes positive, one with extra-capsular spread. I never asked what stage (would have scared me anyway) Right side tonsillectomy, radical neck dissection right side, maximum radiation to both sides, no chemo, no PEG, age 40 when diagnosed.