I think she is will written character, and MD well played it! to the point she really deceived us!
she is negative from the start with a sweet mask! maybe she herself dont know this dark side of herself!
she always tend to do what she think what made her great in eye of the others, and get used to have what ever she want!, specially attention from all around her and credit for others doings
and while i was always wondering why she don't recal the gunpoint jock, now by her obsession about imlie's sendoor I think she have it in her mind all the time, but don't want to confront it directly, it is easer for her to attack imlie rather than recalling the accident and questioning Adi directly