I don't know if I'd call it "warning" him, but you can let him know what you did and why. Keep it civil and matter-of-fact.
Me: 44, Wife: 39 M: 17 years T: 20 years Bomb on 08/25/09 1/13/10: MC started 1/28/10, 2/8/10: More bombs 8/28/10: Wife moved out No talk of D, no movement