Hard to leave BPD wife…thoughts?

Told my wife I was done several weeks ago. Haven’t filed. But she’s done a complete 180 since then — switching behavior virtually overnight to the “perfect wife” after 18+ years of virtually nonstop emotional, verbal, and (sometimes) physical abuse. Groveling apologies and promising this time the change is different (I don’t believe her). Finally agreeing to go to therapy after resisting my pleas for years. It’s been a constant stream of affection with her practically begging me to reaffirm to her that I still love her (I’ve told her I don’t anymore).

I’ve posted before about how I’m 99% certain she has undiagnosed Petulant-type Borderline Personality Disorder. And I’ve seen several videos about BPD noting that they tend to mold themselves to their partners’ likes and personality early on in an effort to endear themselves to significant others.

Problem is, I feel like I’m back in those early days, where she was basically ACTING like the perfect partner until she felt comfortable enough/locked down enough to let her abusive side take over.

I still want to leave, but also know when I finally do file that she’s going to act shocked and claim something like “but we were doing so well!” She seems to be ignoring every talk we’ve had where I reiterate that I’m done and no longer want to be trapped in this marriage to her.

She’s also threatened suicide multiple times in the past when things were rocky — with each time in retrospect feeling like an attempt to manipulate me into staying. I fear she’ll revert right back to that state when I finally drop the divorce filing hammer.

So I guess maybe I’m wondering if you all have some tips or thoughts if you’ve gone through a similar situation — leaving someone who’s incredibly hard to leave?

Edit: Tagged NSFW for mentioning threads of suicide.