Detach w/love,
The smear campaign is sometimes the unfortunate parting shot that BPD's take to absolve themselves from looking like the bad guy. In their child minds; everything is about winning.
So ya. Her intention is to punish. Because they tend to think that everyone thinks like they do. So they try to beat you to the punch by trashing your name. In her mind she needs to reverse the truth so that she's the proclaimed innocent one and you're the ___ty deadbeat. But it's all kid games so rise above it.
Yes it hurts because it's violating, boundary busting and even more insidious betrayal but it helps to know that these tactics only make them look bad; not you. a
The reality is that once we're done with them they have
absolutely no power. Bullies never do. Go no contact and ignore everything else. I don't care if you have to tie your own hands behind your back.

So do yourself a favor. Talk is cheap. And you have no control over the things she'll say so don't stoop down to her level because
the truth defends itself. Anyone who turns their back on you because of her words wasn't your friend anyway.
Stand tall in the fact that she's out of your life for good. In time this so called "friendship circle" will soon enough see her for the character flawed person she is.