I dont see the harm in seeing her one last time, if she wants the closure. Not being able to see you or communicate with you is just making her want to see you more than ever.
What exactly are you afraid will "relight" if you see her again? You obviously recognize that the relationship wasn't good, and as much as she cries and threatens, she probably realizes it, too. She's in shock right now.
Her actions are definitely over the top, though..