Once you let a malignant narcissist into your life, watch out. They are like raging bulls. In the beginning she appears to be very nice. This is when she's getting to know you, or, more accurately, sizing you up. She'll ask probing questions as she explores your personality, taking careful notes of your strengths and weaknesses. Later, as the relationship no longer serves her purpose, she'll strike you in those weak spots.
Much of the destruction caused by a narcissist is what's been referred to as "collateral damage." This is when the other important people in your life begin to march in lockstep with the morally disordered person. This happens because a narcissist makes a point of getting to know your friends and relatives.
Because folks with this particular disorder tend to be suave and persuasive, people are drawn to them. So they acquire a certain amount of influence. As the narcissist gets ready to cut you out of her world, she then tries to pull those close to you into her camp. This is accomplished by subtly manipulating them, as the morally disordered person finds a way to meet their deepest needs. That way they are "indebted" to her, and will generally go along with her game.
Or, the abuser may go so far as to spread lies about you, so the people who once trusted you now doubt your credibility. Why would anyone believe such outrageous falsehoods? Narcissists are very persuasive, and they skillfully mix truth with lies to make their story look as if it holds water. Plus, humans are weak and are easily controlled by these master manipulators.
If you suspect you have a female predator in your life, or you know you do, cut her loose immediately. The longer she hangs around, the more of a mess she'll create.