This is so sad.. But if I were him, even if it breaks my heart, I think I would stil exorcise Mitsuba. Mitsuba seems to really fear himself for eating supernaturals, and even drooling over living things. He might be dangerous for living person in the future.
Still, I know it's not fair for Mitsuba. Seeing the supernaturals' relationship with the humans in the past, it really always ended up in tragedy.