I have read posts like yours 15 times in the last few months. Saying almost the same thing. This is a very common phenomenon and I think it is part of the pathology of our programming at the hands of our Nparents(or Ncaregivers.)
I've noticed that a lot of us have lingering issues and internal thoughts that are very similar to what people who have been in cults have experienced. We also seek validation from people who are similar to our N's.... often without being aware of it. This is a great thing to be aware of and to avoid. But recognizing it is the first step.
One of the things my mother did to me was that she sent me to (what is now largely accepted as a self improvement cult) when I was seven years old. Her active involvement in this cult lasted only a year or two, but I think it's no accident that she, a raging narcissist, forcefully imposed on me the very same conditioning that other ACONS have spoken about.
Narcissism is a cult, whether it is formal or informal. And we as ACONS were conscriped into the cult against our will. And by the sounds of it, your experience was up there with as bad as it gets.
What you've said is something I have experienced, and heard countless other ACONS describe. Almost verbatim.
What helped me was watching some documentaries and videos about leaving cults. I'm not going to call anything out by name here, (just in case there are some adherents reading who may be offended or argumentative) but there are some videos online from Former Cult Members, people who realized that they were being abused and manipulated, and fought to get out. And these are adults who got sucked in and then had to get out.
The way I got through this is through my faith. Reddit is absolutely 100% not a 'faith friendly' forum, so I won't go into that here. In fact, I predict at least one comment attacking me for even saying that I have a faith in something, and I apologize in advance for the time it will take the mods to remove that comment. (Reddit is what it is, and it has it's limitations in this area. If you have any kind of spiritual or religions inclinations, reddit is.... nope.) But my faith is literally what got me to where I am today.
The overriding 'killswitch' of all these thoughts you've described is realizing, knowing, believing that you absolutely do not have to listen to this person anymore, and what they taught you is absolutely wrong.
Also, realizing that you don't have to "prove" them wrong.
They're just wrong. And you can leave them in their little made up world and walk away from it, no matter how much they demand that you "prove" them wrong. You don't owe this person anything.
Also, the other key I have found is to stop 'evaluating' myself. There is no more desire to 'do more' or 'be better.' I see myself as what I am, not at all what I do.
I have an internal compass that is not pointed towards the narcissist values i was instilled with. I've moved away from 'the world' and, to steal a phrase, that has made all the difference.
Interestingly the people in my family who still interact with my Nmom, are still chasing the accolades, they are still in the N cult mindset of 'look at me, look what I've done, look at my accomplishments!' Not only my sister but my aunts and cousins too.
In the end, your worth is not determined by your outward actions. This idea is kind of anathema to a lot of modern society, and I think that is related to the prevalence of narcissism and malignant jealousy.
I have realized that this issue that you are speaking of (that I have seen so many other ACONS speak of) is largely a philosophical issue - it speaks to our deep beliefs about what it means to be human.
I now see myself for who I am, not for who my narcissist mother and stepfather told me I was.
I am 'better' every second of the day, because I now see who I really am, and what I am truly proud of myself for. :)
That may take time for you, but I wish you all the best in getting there.
Hope this helped.