A narcissist is a self-centered person without a normal conscience who believes and acts as if he (or she) is the only person in the world who is important.
This is a problem women are sharing in my upcoming book, “99 Things Women Wish They Knew Before Saying I Do” and I recently posted this answer to the question on a website.
This is an incredibly important question and a very challenging problem. If you are in this kind of relationship you have been torn down and made to believe all problems are your fault. Besides that, the charming narcissist may have separated you from your family and friends or convinced them that he is perfect and you're the problem.
Your physical safety is a primary problem. If he has made threats, take appropriate precautions. You'll need all the support available from friends, family, professionals and even a Women's Shelter.
Don't get discouraged. Many women make several attempts before they actually escape.