I can only speak from my experience. And this is a question I've been asking myself.
The enablers in my situation (my dad and sister) refuse to allow me the reality of what happened and refuse to allow me space to have any sort of feelings about what happened. So they emotionally abuse me like the original person (my mum) as she does all that. And my mum must be narcissistic. It's more than being selfish. I view selfishness as a thing that can be changed if the person realises it is a selfish act. And the way people realise that is by understanding the impact that behaviour has on the other person, and cares about that, and then thinks they can do better so change that behaviour.
But also, one person's selfish is another person's asserting themselves.
But narcissistic behaviour is crazy making. It's changing reality. It's being clever with making the person feel they are wrong, their perception of reality is wrong. Which ever angle the person comes act, there is a way of manipulating it back on to them. Crazy making.
And the enablers follow that.
There is no empathy at all on the impact. The emotional state of the person they are abusing is of no concern of theirs at all. Or if it is, it's entertainment and delight that their behaviour causes distress.
I don't know if I am explaining it correctly.
Yes you have perfectly explained what you happened to you. I think it's good that you are illustrating it so clearly.
I'm really interested about words and the terminology we use. I think some people mean or understand different things to others when using some words. For example I get the impression that selfish, arrogant, egocentric, egotistical, egoistic, vain, attention-seeking, megalomaniacal, narcissistic are all a bit blurred together in my mind.
Reading your account I would first say it seems your mother was manipulative and cruel, and your father was negligent and therefore cruel. From this paragraph you've written I wouldn't automatically think of narcissism.
In my mind, wrongly or rightly, I associate narcissism with a need for validation from creating an illusory world that reflects back that need.
So a grandiose narcissist might show up late because they get a power kick out of seeing the people waiting for them, seeing that those people wanted them at least enough to want them to show up on time.
Or a vulnerable narcissist might complain about being taken advantage of after doing a load of chores that nobody asked them to do, so they can get a power kick out of positioning themselves as a victim of people around them, perhaps to get their reassurance.
Both cases are delusions of grandeur. I would guess both are based on deep insecurity, possibly stemming from not feeling loved enough as a child. I don't yet see how your enabler father and sister were narcissists too. Could it be that they felt rewarded by your mother for letting her play out her game of mistreating you?