Hops, I'm finally out from under paperwork (mortgage app - ah, the agony of such DETAIL, right??)
This is such an excellent topic; it gets to the point of something I've been trying to articulate for while, for myself. Like you, I can go off for hours (well, more like days) ruminating and going over & over things I feel, related to situations and the Ns (or other wackos) in them. These people are unfortunately a fact of life, I think. And I've heard there are theories about Nism becoming more prevalent in society lately (maybe it's just awareness of it).
One thing I've caught myself doing in my obsessive thoughts is analyzing the N to death... going over & over the "he said/she said"...trying to find some logic, some magic solution... fantasying about "having the floor" long enough to say my piece about it all without any excuses/justifications from the party involved. In other words, I'm making my thoughts & feelings all about the N. You're absolutely right, that this is unpleasant and toxic - I think, it's almost a secondary wounding that we do to ourselves. I think it's high time I shifted my focus away from them.
But even worse, if "it's all about the N" in our thoughts/feelings... well, isn't that the result they want? We already know that there is no way to change them. Even Blago - the ex-Mayor of Chicago - wasn't stopped by removing him from office. He's published a book blaming lots of others for his actions. And doesn't it take up so much space/time in our lives ruminating on these people... that we often forget that we can change... and in doing so, make ourselves safe and more comfortable when we must interact with these kinds of people? That's my restatement of your original question, I think.
Your question completely "rang my chimes" because I've been trying to identify and define the same thing for myself. One thing I was reminded of this morning is: take care of myself FIRST. If I'm putting myself first, in my thoughts/feelings, then I get the opportunity of choosing - in the moment - of whether I want to focus so much of "me" on an N. (that's a no-brainer, huh?) I've also heard you refer to N-spots... and if you don't mind unsolicited feedback, I don't think there's an N-bone anywhere in your body!
That fear of being Nish... is part of the illusion Ns use to manipulate us, I think. I see it happening subtly over time, that like genetics, we fear that simply by osmosis we - our SELVES - can't help but acquire the same traits. Not only is that unacceptable, in a self-reflection, but it's also reinforced by Ns... so that any normal "take care of myself first" thoughts, feelings & actions are reprimanded, punished... reinforcing the idea, that somehow, some part of our selves is - or might be - just like them. And in reality, yes - if we truly stand up for ourselves and demand that we be treated fairly - well, it's dangerous. Just like it was for my subordinate and my old Nboss.
So, there are two "problems" here. Avoiding the secondary wounding of thinking/feeling "all about them" and also the fear that if we do take care of ourselves first - something bad will happen. THAT is a rock & hard place... until we change ourselves. I can deliberately not spend time thinking about my brother, thinking of ways to "fix" him or explain my reality to him and hope that he cares or understands. Yes, it means he will continue to attack me for things he did not do and could have; simply because I did engage and he didn't. Until - or even if - he ever understands that he doesn't get to make the rules about other people's behavior and reality... I can't - I really am responsible for - not letting him stop me from doing what it is, that needs doing... or saying.
I'm really not afraid of him getting angry with me or attacking me. That's just the "old reflex" that prompts me to fight back. I can choose to not take his words personally, as if they were authentic feedback, because what he's doing is projecting blame. And the other people involved are well aware of this. I really don't have fight hand to hand with him. I can simply disregard his criticism and unreasonable demands. I don't have to explain the "rules" in the business world to him... he's made it very clear that he doesn't want to be engaged in the process, the way it's "played". And this time, he doesn't make the rules. Not my problem that he doesn't like them, either. This world doesn't revolve around him and he doesn't control it. OH... and I don't either; I'm merely responding when prompted for feedback or decisions. I don't need to consult him to have an opinion and I don't have to know what he thinks - to speak myself. I'm not at all worried about "how this looks" to others, because this is the way things are done in reality.
I can do that, because neither of us has a "power" advantage over the other. An Nboss situation does put one at a disadvantage, being dependent on the income and the "good graces" of someone we would much rather not have a thing to do with. So, it's important to pin him down on what he wants - preferably in writing, like an email. That way, when he denies he said it - you can show him proof. It's a lot of extra work for you... and it's not a 100% guarantee, either. Always ask for clarification from him - he'll like this - by restating what you think he said. He's not interested in your opinion, most of the time - and if he does ask, it helps to stay as matter of fact, as possible. If he tries to blame you for "sins of omission"... you can always remind him you weren't asked; you were told what he wanted (and the proof in writing is useful here).
Finding ways to limit the personal interactions is important when someone gives you the creeps, too. It sounds like you don't have a lot of ways to insure your physical area is N-free...
... so sensory stuff can help; soft relaxing music (Pandora is a good computer choice), scents, talismans - like emotional "worry beads" (I kept sea shells for that purpose in the office)... even white-noise machines (I liked ocean waves)... are non-threatening, non-triggering ways for you to define your "safe zone" and purify it of the noxious intruder. These things also helped me re-center myself after having to interact with Nboss; re-establish my own equilibrium, emotionally. Even just making a cup of tea would often be enough to brush the emotional debris off... for me to go on. And no: smoking never worked as well, because that was an "invitation" for me to start ruminating - rewounding myself. Yet it was still a reflex...
and what I needed to change, needed to learn was how to reaffirm myself, validate for myself that he was crazy, and let it go - quickly - instead. And just "do" without caring about right/wrong, consequences (if he didn't ask my opinion), or even if it made sense. That was the absolute hardest thing for those of us in the departmental support group: learning to not care, because we were all programmed to do the best possible job, anticipate negative consequences, and avoid them. But it was the only way we found that we could survive in that situation; if we cared - we hurt about things it wasn't in our power to change.
It is de-humanizing, granted. And that's why the "take care of yourself first" mantra was so popular. We truly hated being in that position. We took turns being outraged that our only choice was to not care - and trying to talk each other down off those ledges until one by one, people found a way to leave.
The only real regret I have is that I covered his ass, so long - saved him from his own incompetence, arrogance and stupidity over & over. And my subordinate's approach - that of being a "Cassandra" and pointing out the errors and problems and injustices all coming from him - is what really got her fired; everyone wants to pretend that the "Emporer has clothes"... and because she was RIGHT and cared enough to say it loudly & repeatedly... she was a threat to the illusion... and that would've made a lot of other people look bad, too.
Gosh, I hope in all that personal "processing" there's something you can use, Hops! I was in that job for 9 long years. Way too long.