Malignant narcissists are dangerous predators. They also know how to work within or around the law, so they don't get in trouble. Technically, harassing someone else is illegal. But a cunning and clever narcissist knows how to get around this obstacle. They abuse incrementally, usually while no one else is watching. That way, there are no witnesses, and, if you do complain, each incident will sound petty and trivial. Someone hearing your complaint will probably assume you have some major issues.
Because malignant personalities are hellbent on destroying their target, they typically recruit a team of individuals that I like to refer to as "flying monkeys," named after those nasty winged creatures in the Wizard of Oz. These pathetic souls take turns delivering blows as well. So you really can't complain, because you'll sound crazy if you do. Of course, all of this is either done without witnesses or in the presence of "neutral" parties.
The people watching this unfold have chosen to remain "neutral," which means they really aren't in your corner. That's because they allow the hatefulness to run unchecked. Because the narcissist is so nice to everyone else, in order to ensure that you are isolated, all it would take are a few words of support from these people. If these were spoken, things would be different. This is why I have little sympathy for the onlookers, also known as the enablers.
Eventually, though, justice will catch up with a malignant narcissist. This will happen she didn't know when to quit. By the nature of her disorder, she is reckless and impulsive. Narcissists are also prone to making huge mistakes, also due to their impulsiveness.
As a Catholic, I also believe each will be judged at the end of their lives, in accordance with their deeds. So, the malignant narcissist who created so much misery in your life will eventually be held fully accountable.