2 choices. Ignore and pretend they don't exist. Fight back. Third option is to give impression of ignoring whilst fighting on the sly but this is fighting back. Regardless it shan't end way you would like. It never does. There is a game some people play. It's called I'm going to fu*k you before you fu*k me. Passive aggressive behaviour uses rules of this game a lot. Those who like to provoke and harass thrive off of this (once they smell blood). Its really the same game. Again, choices are to ignore or to fight back. Remember with narcissism, there is no winning. Ever. Best option that bothers them most is to ignore.