I think being mean to people in high school is healthy. It's sort of like you're in this situation with all these other kids and sometimes you need to get your aggression out. And if you'd had people be mean to you before, it really does build character.
Life had stopped for her a long time ago. She was so out of touch with her feelings that she had no joy in her life and no concept of the fact that she could be wrong. She delivered her care of her insane patients in a killing manner, but she was convinced she was right.