Reaction to divorce?

[Methos]

Hi folks,
It’s been a while since my dBPDw left me. I regularly read through the posts on this topic trying to figure out my next steps. Through the years we were married, she threatened to leave more times than I could count. She also threatened divorce many times.
Since she left, she hasn’t tried to contact me, but I know she occasionally drives through the subdivision where I’m currently living. When I see her driving, she doesn’t acknowledge me and drives on as if she’s visiting someone in the area. When she moved out, I think she thought I’d beg her to come back, but after years of emotional abuse, I wasn't eager to re-experience her rages.
I’ve written a letter to her suggesting it’s time to officially terminate our marriage. In the letter, I give her the option of starting the process of divorce, but I also tell her that if I don’t hear from her in 60 days, I’ll get the ball rolling.
She experiences severe depression at times, and that’s the only diagnosis regarding her mental health that she accepts. She has been diagnosed with BPD twice by qualified mental healthcare providers through the years, but she won’t accept that diagnosis. I’m concerned about her reaction to my suggestion that we officially end our marriage. As far as I know, she has never actually attempted to kill herself, but she has threatened it often and she has mentioned ways she’d end her life.
I haven’t spoken to her since she left and I obviously don’t know her state of mind, but I think it’s time for both of us to move on. Any thoughts?
Thanks in advance!
Methos

[Turkish]

It's tough to be left in limbo, especially after so long a marriage.

Is the point of the letter to nudge her to maybe come back, or to close this chapter of your life and move on?

She'll react how she's going to react, and depression is brutal enough, nevermind BPD, yet you can't be held hostage by the unknown future.

If you truly desire divorce, then I would initiate it. At best, she won't. At worst, she'll be one up initiating it.

[Methos]

I've witnessed how rapidly her mood can change and that's what concerns me. She always sees herself as a victim and never takes responsibility for her actions or the things she says. In her mind, she's perfect and has never done anything wrong. If she gets angry, it's always someone else's fault for "making" her angry. When she gained weight, she said it was my fault for not "making" her "go to the gym." She couldn't see that it was her fault for eating a lot of junk food.
When raging, she has frequently said things like, "marrying you was the worst mistake of my life" and "I don't love you, I've never loved you and I'll never be able to love you." Much later, after she'd cooled down, she'd act like nothing unusual had taken place. Not once did she apologize or even seem to recognize that she'd said some very hurtful things. When I'd ask her about the things she'd said, she'd call me a liar and deny having said what I distinctly heard her say.
I believe most men would've divorced her early in a marriage.
No, I'm not interested in having her back in my life, but I also don't want to be the one her family will blame if she ends her life.

[Turkish]

It's my fault... I experienced that as well in so many things...

Divorce by definition is adversarial, even the best of them with low conflict. I'd take control if I were you. Her emotions are all over the place.

My ex once told me that she needed someone to "lead and guide" her. In that I "failed" she told me.

So I lead and guided in the Breakup. We weren't married, but had to negotiate custody, physical and $ child support and I gifted her $$ to move out. She seemed paranoid of going to court, so we did it outside, and I Paid for the lawyer. She was served by mail to avoid possible humiliation of a process server. Everything was by the book/guideline. She initially wanted no filed custody. I wouldn't accept that. This isn't an issue in your case, but it's valid not to accept what you don't want.