Yikes, I'm really sorry to hear someone is this evil and stupid
Could you maybe offer to take both guinea pigs for a few dollars and mention that the setup will probably sell better without the animals, then the female doesn't cost a fortune if there're complications with the birth e.t.c...?
I know taking both'd be a nightmare and I bet she'd still say no, but it might be worth a shot if possible.
I really do hate people like that woman