I don't know much about the merlin legend, but in almost every version of the tale I've read about or seen on screen, Morgan le fay was an evil sorceress, Merlins rival/enemy and the big bad of the story.
In this version of the tale she seemed not evil at all, only surounded by bad people who just used her.
It really depends on what versions you've read or seen. In medieval sources, she is an ambiguous character, either friendly or dangerous according to circumstances. Her hate for Guinevere, for example, and by extension for Lancelot and Camelot, stems from the queen's meddling in Morgan's love-affair with a knight who happened to be Guinevere's cousin. Morgan never forgave her, and kept a lifelong grudge against "untrue knights".
"Occasionally I'm callous and strange."