[Angus]

She's just an arrogant, over-privileged, intellectually challenged, emotionally bereft, nasty piece of work with an unwarranted sense of entitlement and a warped sense of reality.

Does that make her "mental"? No, because genuinely mad people are unaware their behaviour is inacceptable or that it impacts on others. Not only is Caroline aware of how she is perceived and is calculating about what she says and does, she absolutely revels in hurting and upsetting others. In my book that makes her a marginal, amoral human being whose lack of empathy denotes a borderline narcissistic disorder.