"I've been contemplating a rather severe letter in response, but I haven't gotten to it as I don't believe anything I can say to him will be effective." I doub

"I've been contemplating a rather severe letter in response, but I haven't gotten to it as I don't believe anything I can say to him will be effective." I doubt whether anything you say to _him_ would be effective. But why not write a response and then post the three letters (your first, his reply, your response) to a blog or website? If you publicly reveal the weakness of his position it could have some effect.