I would recommend taking the letter to a local attorney, and if he/she thinks you were in fact defamed, have the attorney send a letter to these people demanding retraction. If you get that, then you can disseminate it to anyone you want as proof that you in fact did not do those things.
Could there have been a better, more comprehensive, useful, understandable response here? NO! Not in a million years.
Ms. Sargeant, your contribution here is a stellar response that merits wide circulation and citation throughout the Avvo Q and A on this subject. I have no doubt that you can educate and persuade a jury on all kinds of legal issues with outstanding results.
Thank you so much Ms. McCall--coming from an attorney of your caliber and reputation, you comment means more to me than you'll ever know.
Ms. Sargeant, response is well taken. The letter must be reviewed, and you need some sort of provable damages.