Sounds cruel, but take him back where you got him. Get your money back.
My wife is already attached. We bought the dog from the family of one of my JROTC Cadets. We had bought the dog and left him with the family until after we got back from a cadet leadership camp. During the trip, I found out the kids mother was leaving her job to take care of her sister (cancer).
If they were actual breeders I’d demand that they pay for part of the vet bill but they haven’t got much and the litter wasn’t intended. This could have been avoided with a $20 Parvo vaccine.
If I could do it again, I would have either taken the dog and boarded it with our other pets or at least taken him to the vet for shots and brought him back.
Usually it takes 3 to 4 vaccinations before a puppy is relatively safe from parvo. Eight weeks is usually when either the first or second shot is given. It wouldn’t have mattered much if they had spent the money.