Narcissism ? Is it dangerous? Is it considered as a psychological disorder? How? Why or why not?

I believe it is, yes, I was common-law with my boyfriend and he was definetly narcissistic. In fact, I would place my final $10.00 that he was an undiagnosed narcissitic/personality disorder. He cared absolutely for himself only, no one else. He would not pay child supprt because he felt that his ex-wife didn't need it. He was extremely secretive with everything and it got so bad that the emotional/mental abuse that he inflicted on me caused me to finally break down and walk out. (It was my fault for staying, not his by the way). In any case, I believe that someone who is so into themeselves that they fight against societies rules/regulations/laws is definetly dangerous. To me, these type of people/personalities, can be a ticking time bomb. I lived a horrible existence with him. Now this is a most extreme form. I would say it depends on the situation.