Narcissistic injury

After recently realizing that experience in my life fits pretty closely to what is perceived to be NPD symptoms, I started googling NPD and related problems and found this concept of "narcissistic rage".

I'm not sure in scientific correctness but the description definitely fits what I've been dealing with.

"My" scenario:

Basically my NPD-suspect person would get really angry for different trivial things or (more commonly) without stating the exact reason.

Usually couple of weeks prior to that they just colder, again without explaining any reason, just gradually colder and colder. Attempts to find out what was wrong or offer help only made things worse (I wish they told me that NPD or similar problems exist in school or something, but I'm from shithole anyway).

Eventually they just go raging.

Their state become uncontrollable, whatever I attempt to say is just met with anger, insults, attempts to hurt me (physically I'm safe, but emotionally... before I learned that NPD/BPD could be a thing I was just plain destroyed) as much as possible, being really mean, mocking my illnesses, etc.

No matter what I try to say (and I really don't answer with same, I just curl up and beg them to calm down -- "NO YOU FU*KING CALM DOWN, I'M CALM" is usual answer.

Maximum rage situation usually ends with me being blocked, driven away, etc.
This often happens just couple of weeks after they say convince me this will never happen again (or, the first time, just few days after they themselves approached me to watch stuff together, like everything's nice).

Of course so far they've come back after weeks/months with another "supply" I assume.

But during the rage as if there's no memory of anything good that happened (or could still happen) I'm just powerless to stop them, the only healthy situation when I'd assume such could happen would be when they really HATE me.

This fits what I read about "splitting" and NPD-people allegedly not being able to accept someone as both good and bad at the same time (but I'm not expert and not claiming that it's actual thing common to all NPD, please don't beat me up, I already get enough violence from an NPD-ish person I know).

Questions:

• Is it real? (seems quite common if I read posts about abuse);

• Have you ever experienced it? (Following questions are for the case if you have):

• If you're okay with it could you please help by sharing your point of view -- what is it like? Is it that bad? You really hate the person and do not recall anything positive about them? Or is it just a "tactics" to get rid of unusable "supply" sooner?

• Can something be done to calm such person down if the rage has already been triggered (I believe nothing can be done to prevent it as there is never a definite answer what exactly causes it anyway, could be a thing which was normal just 2 days prior).

• Is there some cooldown period after which such person would be able to perceive me as "not 100% bad" person? Could something be done to accelerate it.
  Or should I assume they "hate" me only when they find no use for me but when they're desperate for whatever I can give them they would pretend they forget their hatred/sincerely forget about their hatered?

Sorry for such questions, I'm just frightened of the situation and would like to know as much as possible of the point of view of someone who could've experienced it because articles like "Run, they'll kill you" are not incorrect but not too helpful if I cannot/don't want to run yet.

Thank you.