So sorry to hear this news Tx...
Now I'm not a mother, but I know that if I did have kids, and was put in your situation, I would have the dog PTS. I know its hard, I've lived through this experience more than once, but it really is for the better! I don't think you want another woman's son to be bitten like yours was, so giving her up for adoption isn't really logical, IMPO.
Of course getting a second opinion just to be sure won't hurt, but I think we know they're all going to say the same thing.
It was extremely brave of you to be honest with the vet, showing the pictures and all...
In the end, it IS you and your family's decision. Keep us posted! :wink: