Hi, Welcome to Health care magic forum.
As you said that is the only alternative, if it is confirmed, you have to get his semen examined, for confirming the failure of the vasectomy
Any how as there is no betray from your side, be confident, and brave.
Take more of green leafy vegetables, pulses, sprouts,and
protein rich foods to have a good health.
Wishing for a quick and complete recovery. Thank you.