She's an anti-hero, like Wolverine, from the perspective of someone who was much more consciously a villain in the past and still prefers some of their methods.
Wolverine is no anti-hero. The only time he's ever worked for the bad guys was when he was under their control. He's kills bad guys but then so does James Bond, Indiana Jones, Rambo, Ahnold and John Mclaine.
Emma is evil. She takes pleasure in causing pain, anguish, and manipulating people. Fitting for a serial rapist. She was just crafty enough and picked the winning side. There is no moral ambiguity there. She doesn't believe in what Xavier believes in. She thinks mutants are superior to humans, but unlike Magneto she's willing to wait on inheriting the Earth. It's why she's always spewing out that elitist crap. She's a disgusting waste of a person and Marvel needs to quit pretending she's a good guy.