What to do if my hubby has throat cancer positive for hpv. does this mean he cheated?

Years to develop: HPV driven cancer of the throat takes several years to develop after the infection. It is not an immediate or short-term process. The infection that led to his cancer would have occurred several years ago. It would be nearly impossible to know when the infection occurred. Without knowing a detailed, complete and honest sexual history it is impossible to use this alone to implicate cheating.

No: Nobody knows how or when throat hpv strains are acquired but these aren't the sex strains. I am sorry your husband is sick. Even if there was someone else in the past, this is not the issue now. You may nor have him much longer. Love each other. All the rest means nothing.