Hi Ami,
Perhaps your empathy turns off at times, or is on flicker instead of reliable. That would seem like a natural consequence of having a severly N-istic parent, I think. Even though many children of Ns have kind spirits most of the time, I think the connectedness, the flow that normally happens between people who love each other, keeps shorting out.
Perhaps yours turned off because you didn't feel like coping with his pain? Maybe his pain short-circuited you, since you have buried so much pain yourself, that if anybody gets near triggering it, your emotional system shuts down? Even if it is an Nspot, I assume that people develop them out of a perverted (not by the person out of "badness", but by what their experience in life has caused in them) instinct of self-preservation.
One of my Nspots is entitlement. I loathe it but there are times when I catch myself being "special"...surely those rules don't apply to me, or surely my wanting my mother's house is right (because I want it), etc. Surely I'm entitled to not be unhappy in a job because I'm so smart, etc. Uggh.
I have found, though, genuinely experienced, that the more I am in touch with compassion for myself, the less my Nspots act up. And that's a deep comfort. I am growing all the time. I actually like myself much much better than I used to. Not swelled-head liking; I just feel like my own friend at last.
Hope that makes sense, and I hope it's helped you to talk about these things.
(Another one of mine is being a voice hog. I'm doing way better with that one too. But it was a struggle for years. Now, more often than not, I really do only want my own turn...not everybody's!)

gently,
Hops