On one hand, the compassionate side of me feels for him. It's a scary situation. Everything is going down the toilet. But on the other hand...you do not deny your friends. You definitely do not deny your God. You never, ever, ever deny your friend who you KNOW is God, and Peter knew. Maybe he was doubting, but still. He knew. More than any of the other disciples, he knew.
Also, part of me is annoyed at the servant girl for being so inquisitive, but I am also the sort of person to shake someone down. So I shouldn't really judge her for that either.