I have also been reading about "The Dark Triad" and covert narcissism and quite frankly upon further investigations there are some astounding similarities to my relationship with my W and WAS/SAS. It's uncanny.
It's common to re-write, or re-frame our ex's as villains we're lucky to escape who will do poorly without us. Often, the WAS has already done this, and the LBS follows suit when their odds become long.
If your ex was a narcissist and everything was about her--why did she stick around for 3.5yrs while you didn't work, were too clingy, and didn't have a disability? Why did she stick around for 7.5yrs when you had a disability? My XGF's XH left after 25yrs of marriage the month my XGF was diagnosed. Either way, he was on the hook for $$$, but that freed him from the rest. That XH was never diagnosed with Narcissistic Personality Disorder. He was just selfish with baggage around caring for a dying parent years before.
I have a friend with an XH who is a narcissist. The week she won in court against him their son graduated. The son was proud of his hair. The XH shaved the son's head in retaliation. Narcissists lack empathy.