Wiktionary
twist the knife
vb. (context idiomatic English) To deliberately do or say something to worsen a difficult situation or increase a person's distress, irritation, or anger.
Usage examples of "twist the knife".
The spirits weren't content to destroy her, they had to twist the knife.
Lots of blood, and I want to hear her scream as I twist the knife in her.
A lot of people would have used it as an excuse to twist the knife a little deeper.