Thank you for posting your comment. Reading your words made me feel like you may have been spying on my 13 year relationship with my NPD/ BPD wife.
Aside from the advice in the actual post your words really resonated with me. I have also recently come to many of the same conclusions about the finality and futility of remaining in my marriage.
I have physically, mentally, and emotionally gone through many of the negative changes associated with being in a long term relationship with a personality disordered person. I, like you, wish I would have listened to my intuition when I noticed the initial warning signs and gotten out earlier. So much time has been lost and severe damage done to me and my children over the years and all in an effort to keep my family intact. I realize now that the trade off for keeping the family together is not worth the price of subjecting me and my kids to dysfunctional behavior.
I love my wife but I've come to fully embrace the fact that mental illness is real and I cannot "fix" her. I am not her "God". I hope at some point she gets help but from the research I've done those odds are "slim to none". In any regard, my children need me to be the voice of reason so that will require me focusing on making my needs a priority. I hope to be out soon and living independently of my wife.