In regards to responding to H try to remove all emotion. It is stricly business at this point. Do your homework understanding the rules of divorce settlements in your state (which I'm sure you have). Easy for me to say, but take a deep breath and wait a day or so to get your thoughts together. Especially this type of email. Maybe wait 24 hours to respond to this type of email.
Perhaps there is nothing behind threats from H. Just your H being himself. Kind of expected behavior for him.
