Yes, life is too short rgreil, but we need to let off steam sometimes, and to reinforce the point that such behaviour is not acceptable. Too many people, particularly the more well-off I find, think it's ok to treat everyone else on the planet as staff and that there are no important consequences to their actions. You only need to see how some people treat shop workers and waitresses etc. Their behaviour is appalling.
Well done for helping the boy and for all you did Denwand; at least you have a clear conscience for the right reasons. I suspect the other mother also has a clear conscience and can sleep at night because she has absolutely no idea she has done anything wrong. And what a terrible example to set to her son, who will no doubt grow up believing that is how you treat people.