You want others to see the evil. You want others to see the manipulation. You want others to see the pain and abuse you had to go through.
Since this person is very good at playing a character you want to expose them for who they really are. You want others to see all the dysfunction and mistreatment you experienced. Since they know how to appear like a “great guy” or a “sweet girl” it can often frustrate the victims of narcissistic abuse.
You do not want people to see them as this false image they pretend to be. It would help if others could see what you have seen which is a hurtful, abusive, selfish, manipulative, controlling person.
While it is completely valid that you want others to see this person for who they really are, the reality is some people may never see the narcissist like you have seen them.
The reason why is because the narcissist does not have the same relationship with others as they did with you. Your dynamic with this person was different. The only person who will see the abuse, dysfunction and manipulation is another victim.
If you really want others to see the narcissist for who they are here is what you must do.