Child's father is a clinically diagnosed NPD, how do I protect my 7 year old's life?

Custody orders can provide structure and limitations on intereactions between parents and children.  For example, if a parent has an alcohol abuse issue, a custody order can state that the child cannot be a passenger in the car if the parent has been drinking. In your case, you would probably want to make certain that a custody order provided appropiate and necessary sageguards so that your child would not be harmed by any interactions with his father.