What mental disorder did the main character have?

The medication Sarah found was apparently for schizophrenia or bi-polar disorder, though she didn't really seem characteristic of either of those. Schizophrenia gets a bad rap from movies like this, even though by definition, schizophrenics are normally non-violent (not always, but usually), and if she were bi-polar she would go back and forth between mania and depression, which didn't seem to be the case either.

I think the medical term for it is 'bad acting'.

I think peoples' experiences shape who they are too. Remember she said she grew up poor and was always an out cast and snubbed while rich little girls bullied her? Finally she found this rich handsome man who was willing to ACCEPT her and she was happy for a change and would kill to protect what she finally had. My point is if she grew up rich, had more nurturing and compassion from others she would have not been the maniac she turned into. All she wanted was to finally be happy and have a liveable life but because she did what she did to get to that point she was being exposed and didn't want to lose what she finally had. Do you think if she had a better life and grew up happier she'd be so desperate? No, she would of not been so desperate for a decent life and love. If the daughter did not have a well to do father and was treated differently by people then she was, she would have been *beep* up too.

[deleted]