Dealing with an npd ex?

I am severely traumatized to discover that someone I thought I knew and loved for 7 years has a cold heart and a sick mind- and shows overwhelming signs of having narcissistic personality disorder. Our relationship is over, but I still feel an incredible sense of loss for someone that never existed, anger towards being lied to so many times, guilt for exposing my friends to someone mentally unstable, and self-doubt for being put down so many times and being unable to see his true nature. I have nowhere to turn to because nobody I know has been in this rare and painful situation. What can I do to heal? Any words of advice would be greatly helpful.