An obnoxious student I had all year threatened to kill me as I kicked him out of the room, fair consequence?

This kd seems like quite a handful... Not to mention some serious problems... Writing kids up do nothing, I would know this because of being a student myself. Trust me I'm not immature as like the rest of them, kids are never perturbed by getting written up. It's only a joke, the only thing they think is annoying is when you give them very serious consequences. You have to speak to the school about this... You must, you really do. They might be persuaded to do something about it.