The attorney is trying to pull one over on you. He is trying to use you to cover up his mistake, and what he has demanded is merely the easiest way out for him.

The lawyer made a mistake that could result in the Child Support Recovery Agency bringing him up on charges before the state bar association. You are not responsible for that, he is.

The idea of sending the letter to Child Support Recovery Agency is excellent, it is exactly what you should do. Make sure the letter is objective stating only hard facts, no opinions.

What I would add to this is a suggestion that you send this letter along with photo copies of any correspodence recieved from the attorney by certified mail, return reciept requested, to both the attorney and the Child Support Recovery Agency. That will give you proof positive that you made the appropriate notifications.

If everything is as you say, do not consider a personal loan. You were the lawful recipient of those funds, and you acted in good faith.