Radiation treatment to the neck will usually be tolerated in the initial first few weeks. But as time goes on, the effects can and usually do cause issues which must be delt with as they arise. Initially most folks lose their taste, perhaps saliva issues, swallowing issues, and just general eating issues altogether. Personally after my experience, I would not go again without a feeding tube by the third week. As much "fun" as a feeding tube can be, there is not really an alternative to getting your nutrients.
The last two weeks of treatments seem to hit most of us the hardest and perhaps surprising is the fact that he will continue to go downhill for usually two weeks before recovery begins. The effects of radiation are cumulative. Radiation "sickness" is real to many of us during those weeks. And by recovery I mean slowly, two steps forward and one step back.
This is a battle he must commit to, a battle he must fight, and a battle most of us have won. Hard as it may be, the alternative is not forgiving.
We are here for you and your husband. You can also contact any of us privately by clicking on our names. Good luck and good fight. He may not believe it but in the long run this one event may just change his life for the better. And for you, remember, life is what happens when you're making other plans. Let him be grumpy. Let him deal with the unexplainable. It will be OK.