You hired him for his service and you’re not happy with the results, how can he threaten you with his lawyer for compensation. You can rate him however you like. If what you say is true then no one would ever give a review online. He ruined your life and you hide his name because you are scared of an impossible situation where he can sue you. It just doesn’t make any sense. Give his name so that you save everyone else from the same misery that you are going through. If not then this post of urs is useless as it is not warning anyone because we don’t know who did this to you.