I found a book that seems to help me focus and give some assist in dealing with people with Personality Disorders:
Say Goodbye to Your PDI (Personality Disordered Individuals): Recognize People Who Make You Miserable and Eliminate Them from Your Life for Good! by Stan Kapuchinski M.D.
I find if I read the suggestions in the book on what to do before I have an encounter with the NPD ex it helps me script out situations so I am not suckered into another emotionally draining situation.
Hopefully this will help you, as well.