My story. Hope it helps.
I had two Ddays almost exactly a year apart. The first almost destroyed me, but i picked myself up and started working on myself. It took a long time, but I rediscovered the person I was before I lost myself in my M. Funny thing,it turned out that I was an interesting person that people liked. The whole process made me stronger and healthier, so when the real Dday came around, I reacted as we all do, but I was much stronger and did not accept any bullshit. My WW went from a position of agency (information control) to playing defense and trying to mitigate the damage.
I gave her 6 months to own her shit and prove to me that she was worthy of a second chance. She wasn't. Meanwhile, I continued to self improve and detach. She occasionally tried pulling some shit with me, vonfusing the new me with the old me, but she quickly realized that it wouldnt work. I remember her breaking down a few times,not for the pain she caused me but for the life she had lost.
After 6 months had passed, I informed her I was going on a solo road trip and I would be back when I got back. I told her not to contact me in any way. She agreed because she knew I no longer gave a shit. On the trip, I spent time reading, Journaling, thinking. When I returned, I asked her a simple question: "What are you doing to help me heal and repair the damage you've done?" She responded (and I kid you not) "I can't be there for you until you're in a better place, because you make me feel too guilty." It was then that I stopped lying to myself, thinking she had the capacity to change. She has really never grown beyond her late teens/early adult self. I told her we were done and went to bed.
It's been almost 10 years now and in less than two months, she will officially be somebody else's problem. Meanwhile, I am doing better than fine. I'm good. I wouldn't say happy (I don't really do happy) but content. I love my peaceful life. Granted, it was a painful journey getting here, but it was worth it.
Early on, people told me, when you know, you'll know. I couldn't understand that until I got to a place where I knew. Looking back, I made the right call divorcing. My ex and I were ill suited for each other and remaining with her would have amounted to a slow death of the soul. She's moved through a couple relationships with the transition having some overlap (still a wayward), while I have settled into my peaceful existence which I guard jealously.
I hope my story might help I some small way. Its a tough decision and I'm certain you'll make the right one once you get to a place where you know.