I suggest don't play fire with fire. Don't stoop to their level. Leave them to their own devices.
People with BPD have a unique knack of doing things to evoke a reaction from you so that they can victimise themselves and come out of the situation as the victim and you as the perpetrator.
The Greeks have a saying that I quite like... .
"Leave the madman to his madness".
Spot on AussieOzborn. If only I'd taken a back seat today and not entered the madness with him. Sigh.