I think you're right Paulie about Christy being too emotional.
If she were a tad less paranoid, I think her attitude would improve. I can understand why she's frustrated. I can understand why she feels everyone is against her. But if she can even start to bond with even ONE person, I think she'll feel less ostricized.
I wonder if she assumed she was the next to leave, which is why she didn't want to help with the shelter and figured she had nothing left to lose. Maybe she'll see getting spared as a vote of confidence and start to lose that chip off her shoulder.