It's nearing a decade....
Alternatively, (non-violent) retaliation? Seems like there's no downside for this person to be harassing you. Creating a downside might make her think twice next time.
Threatening to involve the police is a common way women abuse men. You can of course involve the police yourself but they often won't listen.
I had an ex try to create a situation where I would be framed for rape by creating fake social media accounts purporting to be me. Luckily she wasn't smart and the police saw that all the accounts were obviously created by her. Yet they still didn't help protect me from further harassment or do anything to her for trying to frame me and making false police reports.
Sad as it is, probably best to just try and ignore her and consider going by an alias online and moving house.
The court system is a big hole to throw money into:
1) It is surprisingly impervious to actual evidence. A woman crying on the stand, with a bunch of fabrications, will be believed. A man showing documents won't be.
2) It's influenced by preparation and money. If the other party is willing to devote their whole life into this, and you want to live anything resembling a normal life, you're basically SOL.
There isn't a magic fairy government agency who cares about this sort of thing.
I don't think there's a solution.
I was modestly famous before this, but I haven't done anything public in a half-decade because of this !@#$%.