I believe my ex-partner is NPD. ... Sometimes I think the kids are so much better at moving on because they don't analyze everything to death. .
It is your job as the adult to think, analyse and reflect on what is happening to you and the kids. It is right that they should not have to do this, but it is also right that you do. There is no such thing as thinking too much, although people who don't want you to think at all may say there is.
His current behavior seems to reinforce my feeling that he is NPD. He last saw the kids 7 months ago, he doesn't call much, he didn't respond at all to the custody documents so I have sole custody and control over visitation. ... I try very, very hard to stay neutral for the kids -- we talk about their dad in our daily conversations and remembrances and I sometimes tell them about our days before kids. But I have also expressed my opinion that he is not being a great father right now. He calls them on the phone every few weeks. .
Whatever label you use, NPD or not, he is not a great dad, is he? I am not sure it is right to stay neutral in this situation, because it is not realistic, and may cause your children internal tension, imo. (But this is just my opinion, and I may be wrong.)
My daughter has a dad who is not a great dad, and I say so. I don't go out of my way to criticise him, but if he is behaving badly, we talk about it. This in turn frees her to say so too. We both admit that she loves him, and at some level I do too, but that he is too damaging to allow into our lives, except on a very intermittent basis. I found it useful to explain 'ambivalent' to her, which allows her to both love and hate at the same time.
But at some deep level I have doubt. .
That is because you are human, and you are a nice person.
I think perhaps the doubt comes because he always presents himself as being cooperative and completely interested in the kids' welfare. But as I write this I can think of many examples even recently when his behavior didn't match up. ...
I'd appreciate hearing other people's experiences to help keep me strong but human.
Ns are very good at saying the right things in order to manipulate us, but you are right in noticing that the actions somehow never quite match the fine words. I used to say to my ex, love is not what you say, it is what you do. He never could understand that one. He thought love was a warm feeling inside himself, and that was all that mattered - as long as it was there he could treat me like dirt and not even notice. It made me feel ill to recieve soppy cards and such from him even after we split up, and I told him to stop. He still tells our daughter that he loves me, but I tell her that he does not even begin to know the meaning of the word.
It is very difficult to be sure of another person 100%, in 100% of situations, and trying to achieve that will be endlessly frustrating. You may find it helpful to move instead to the kind of 'knowledge' required in a legal case, where there is talk instead of such things as 'reasonable doubt' and 'reasonable belief'. If you think that there is reasonable doubt of his ability to be a good enough father to your children, given the evidence you have, then that is enough.
You can have all the empathy you like for a murderer or a child molester. But you would never let them near your kids, would you?? Same with NPDs. Different scale, maybe, but same reasons. Meanwhile, I would say, encourage your children to speak the truth as they see it, and do not pretend neutrality where it cannot exist. In my opinion, and it is only an opinion, they need to know how to speak the truth, because it will empower them for the future.
All the best
C