Sorry to hear your husband is having such a hard time with treatment. While the treatments were brutal, I never reached the point of wanting to stop. I just kept counting down the days.
Jeez... 4 more to go... just 4 more! Maybe a day or two off will help and he can finish. Treatment is traumatic and you're right, he's probably not thinking clearly or rationally at this point. Perhaps 31 out of 35 rad treatments will be enough. He did finish his chemo treatments so that's a positive.
Good luck... positive thoughts and prayers
"T"