I am really sorry for your loss and what you've been through.
Reading all through this thread I can't help thinking that this person has put your guinea pigs in with rabbits, a rabbit has attacked your guinea pig and killed it and injured the other one and rather than have to admit she totally cocked up, she's fabricated a story of pregnancy, etc., I would have told that you had vet records of the sexing and called her bluff.
All very convenient about not knowing where he is buried, etc., he will have an idea of the best place to go to bury him, he's not thick. I would also say that your vets have requested the body for a port mortem to find out the cause of death incase it's anything that may affect your other guinea pig.
Good luck with eveything,x