I've been on the other side of this, where an employee decided to make the lives of everyone around miserable due to whatever problem the person had. In my case, the person made a variety of threats against a variety of people. In one case, the person made wild accusations against me that resulted in frivolous criminal inquiry.

It's not acceptable to make threats in the workplace, and as a manager I will not tolerate it. If you have a mental illness, that fine, but you need to be able to control your behavior.