A narcissist as in NPD (Narcissistic Personality Disorder)?

It sucks. Big time.

I highly recommend the book by Eleanor Payson "Wizard of Oz and Other Narcissists". The best I have read on the subject.

Loving a narcissist ..... will drain your soul and leave you lonely and broken.

I think the last line of this quote is apt:

There are things that we don’t want to happen but have to accept, things we don’t want to know but have to learn, and people we can’t live without but have to let go.

My X has Avoidant Personality Disorder. Someone with a PD should be avoided like the plague.

Has a professional diagnosed him?

My ex-husband was a narcissist. This is what I can tell you, in a nutshell: the world should revolve around him, nothing is ever his fault, he was always a victim of circumstances or being unjustly persecuted, and his needs were the only thing that mattered. They also know how to manipulate. They never truly believe there is anything wrong with them, even if they pay lip service because they know they're supposed to. There is little to no hope that they will ever grow or change because they have no desire to.

That is exactly what they do ...

The interpersonal result of being involved with one is it leaves you empty, drained, used, hurt, and you never get your due process or sense of justice.

The narcissistic defense mechanism compensates for internal feelings of inferiority by using others as self objects to consistently make them feel OK in the moment, which is why they take from others but do not give back. When throttled, there a reaction called narcissistic rage, which is their attempt to get others meeting their needs again. Over time, it is always out of balance, and the longer your involved, the more out of balance it gets.

Are narcissistic people usyaly pathological liars believing their item lies? I think my friends H is one

Going, that is him to a tee. Problem is he is such a sweet person (until challenged). But always full of promises and excuses. I just can't take it anymore. No call for 2 weeks at Christmas. No gift in 3 years.
He is also OCD, so he works very intensely, forgetting me and everything else for days on end. I have no way of contacting him so it makes me hurt and crazy. When he finally comes around he's like, "what's the problem? I was thinking about you " arggg.

Liar? Ha, he's in the perfect profession, sales. He doesn't "lie", he has just perfected telling you what you want to hear! Lol.

My X also has the same basic beliefs. It is never his fault, blah, blah, blah. It's called abuse for a reason. Trust me, RUN AWAY FROM ANYONE WITH A PD!