Knife twister

One level worse than a back stabber.

One who twists the knife after stabbing you in the back.

Goddamn Michelle, she's such a knife twister!

knife twister

One who kicks another while they are down. A person who latches onto another's insecurities and makes them feel worse.

Did you hear what Brittany said to that homeless guy about his life sucking - that was a real knife twister.

Man, Brittany is a real knife twister.