Anything that you resent and strongly react to in another is also in you. But it is no more than a form of ego, and as such, it is completely impersonal. It has nothing to do with who that person is, nor has it anything to do with who you are. Only if you mistake it for who you are can observing it within you be threatening to your sense of self.

Eckhart Tolle, A New Earth: Awakening to Your Life's Purpose