Help, my player deliberately wants to screw with me in the sessions

If DnD is a collaborative storytelling game in which all participants involved choose to gather to have fun, then fun should be had by all. 

If a player's idea of "Fun" makes the others of the group not have fun, then encourage all folks to work together to tell an engaging, fun story. If they can't then there are other tables they can join. 

This is not meant to be a harsh statement. People are different, as are their ways of enjoyment. Encourage them to seek out like-minded folks.

The work necessary to put on an adequate game is not worth having someone break it for their fun alone. 

While that's true, D&D 5e/5.5e really isn't a game that supports PvP in any way shape or form. It's simply not balanced for it. If a person needs/wants to do PvP to have fun, then D&D is not the game for them. There are other TTRPGs that better support this, such as Paranoia or even Call of Cthulu. The way D&D is designed, PvP is simply never going to end well - perhaps outside of incredibly rare story moments that more or less avoid anything mechanical with a group that has implicit trust in one another.