I'm very curious about all of this. How do you know that words would be pointless? Words are, in fact, incredibly effective tools. I once convinced a Dalek that I had the remote to an explosive device in my hand when I was actually wielding a jammie dodger. Eventually he figured it out, but I had him going for a while and, right, that'd be the opposite of the point I'm trying to make here
If you tell these people the right thing, if you can find a way to make them understand what they've done is wrong on their own, then you shouldn't have to resort to the sort of thing that leaves them all messed up inside. What they've done should be enough. They should already know how wrong they are themselves and, chances are, they probably do.