Without gossip, an adult female bully is virtually powerless. Her mouth is her main weapon. She is very adept at dropping hints and negative suggestions about others. Through the years she has honed her skill so perfectly that her listeners oftentimes don't even realize they're party to backbiting behavior.
For a female narcissist, gossip serves a number of purposes. First, and foremost, she uses it to neutralize her target, because she's somehow able to convince everyone else the person in question is a very flawed individual. Gossip also, sadly, breeds camaraderie among members of her social group, who bond together to fight a common enemy. (The target becomes the scapegoat.)
In addition, gossip is used to maintain a narcissist's power base. If everyone around her suspects everyone else of wrongdoing, they won't be able to compare notes and figure out that she's the real troublemaker. If people knew the truth, most of them, unless they had a serious moral disorder themselves, would want nothing to do with her.
Also, if they could see the big picture, they'd realize they are dealing with a very dangerous person, who has the power to destroy, if she decides to turn on them. In fact, that's often what happens to her flying monkeys, whom the narcissist recruits to help carry out her agenda of making sure her target suffers. They play a role in getting her to leave her job, if this happens in a workplace setting. In a social situation, the target has no recourse but to withdraw from the group.
Anyone who allows someone else to be treated this way is an enabler. People who choose this position must watch their own back. Once one target is marginalized, a malignant narcissist starts for someone else.
It is very painful to be a target, and to have others look the other way. That's because they lack integrity. However, this is a bad reflection on them, not you. Although it's difficult to leave a job you loved, or to move away from a group of friends you once treasured, it's necessary. You deserve much better, and you'll find find peace again once you make the break.
What you are leaving is highly toxic. You can rest assured this dynamic has no future. It will eventually break down and dissolve, as it rests upon an unsteady foundation.