Honestly, the thing I will always tell people who experience this is to call emergency services on the person making the threats. Either you've saved them or taught them a lesson. Either way, it's the best move you can make.
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Kid in my class was pretending to hack someone else in the class and then started frantically typing to 'mirror' the counter hack. This was in about 2002 and the total hacking ability of the guy was being able to open that window chat terminal thingy to another machine on the network. I still think about that moment and wonder how he's doing.