The best response to a narc is no response! If you must respond, show no emotion... This can be very difficult, but it will deprive him of what he wants most... A narcissistic payoff from your reaction/response.
Amen!! And then sometimes you just have to walk away even after they're forgiven. You can never forget some people's actions, just simply try to forgive and then separate yourself from their web of lies dysfunction and manipulation. (I speak from experience on this one as you may see...lol)