Discreetly and quickly, my first wife was initially diagnosed with borderline symptoms. It can, and in this instance did, degenerate to Intermittent Explosive Disorder.
In this situation, firearms or weapons of ANY kind in this person's vicinity could potentially wind up with you on the wrong end.
Oscar Zulu, only YOU know your current feelings but please know this:
You will NOT be the person who "saves" her.
There is no logic connected with their actions thus there's no way to "de-fuse" or "calm down" a violent episode.
The only guarantee for you in this is that whatever and however you try to keep "normalcy" and peace, you will be the loser.
As much as it may hurt to do so, your best option is to run screaming into the night, leaving no contact info. Just disappear from her life quickly and completely. The alternative is the eventuality of one or the other of you winding up either hospitalized, incarcerated, or possibly dead, either her accidentally in the process of your defending yourself or YOU, having been the object of an outburst.
There are no winners here. Only the promise of continually deepening misery.
If I can help you at all, my email is in my profile.
I wish heartfelt good luck to you, sir.