I really admire your resolve in protecting your family, killing off these toxic patterns and cutting the chord. I completely understand the pain you have experienced to land at that decision, and I also understand the external pressure you've probably experienced too from other family members / the world at large.
I relate to so much of your family experience it's insane. Right down to the GC sister embedded in the family, treated like a queen, operates in whatever way she wants and is supported, and who has a completely foreign narrative about the family to me. "We are so lucky, our parents did so much for us, sacrificed so much.."etc. It got aggressive in the run up to my wedding. I remember going on my Hen and sitting there like a rabbit in headlights as she rolled out the lines about how amazing our mother was and how we have to honour her at the wedding.
Which mother? The same one that hadn't contacted me in weeks, who was still applying pressure on us to get a blessing by a priest (neither of us are remotely religious) lest the neighbours gossip about our wedding, who hadnt lifted a finger to support me and hadn't visited my own home for 2+ years at that point. I realised the gap was too wide for us to ever be close, the door was firmly shut on ever confiding in her, there's been this dedication of time and resource into her by my mother that I have never known. I've realised recently that grieving who my parents will never be and getting to acceptance with who they are is completely interrupted by witnessing my sister and my mother together. Because she chose her favourite, and she's parented that one consistently albeit dysfunctionally for decades. It's hard to accept "that's just who she is" when I see that invested, obsessive side of her when my sister is with her.
I'm sorry your parents failed you so much when you struggled in your 20s. I find those types of experiences the most difficult to overcome. The hard stuff is less damaging long-term when there's support there for you. I've been most scarred by sitting in complete isolation as I went through those harder times as a kid and young adult. Surely support and compassion at those low times is parenting at its most basic?
How did you come to the conclusion about your family members being narcissists? I struggle with the labels, because there have been good things and times. I've resigned to it not really mattering at this stage. The damage is done regardless. Both of mine are similar though. Both obsessed with status, money, image, material stuff, gossiping and judging others, a strong superiority complex. Performative empathy, they'll talk sympathetically about people in less fortunate positions - as long as those people are below their pecking order and not a direct challenge to them. A strong history of scapegoating - there's been boyfriend after boyfriend with my sister who've gone from love bombed and initiated into the family, to my sister and mother bitching relentlessly about how horrid and abusive / narcissistic / etc they were during the inevitable breakup. That behaviour was the one that disturbed me most in recent years, as I'd come back from my life overseas and witness this elderly woman saying the most bile things about some fella in his early 30s who'd been around every Sunday for my mother's roast for months before. The enmeshment is striking, it's like a brain-washing and it's made it extremely difficult for me to have a relationship with either of them.
I've also found that during one of the hardest but most important years of my life, with a wedding, but so many health challenges that are impacting a really complicated and long fertility journey, and now a career I've had to take a break from - the last people I want to be around is my family of origin.