I’m actually really bothered by this ‘prank’.
Don’t get me wrong I loath the woman.... but this has tipped over into bullying - if KH was doing this sort of thing we’d be outraged. It doesn’t make it right just because the ‘target’ of the bullying brought it on themselves.
Far better would be to ignore her and let her slink away in shame - she’ll turn up working some low level job for the rest of her days and missing what she had, and lost through her own behaviour, which seems a suitable punishment