If you're struggling, consider talking to a mental health professional. It's difficult to stay mentally strong when you're working alongside a toxic person.

Document any damage done with medical professionals.

All of this will make your case in court should your psychopath escalate and you have to take them to court.

Interact with authorities as well build a relationship with authorities concerning the matter.

All of this evidence for a civil lawsuit in court.
Plus you can prove real damages for the intentional infliction of emotional abuse. This is your cause of action.