Don't acknowledge or comment about H's partnership thing at all. He just wants to have it in black and white so he can blame you for standing in his way & making things "difficult" for him.
Here's a suggested response to H's email:
The goal of the mediation is to discuss the division of assets and other pertinent details as they relate to our divorce. As you would agree, the overall goal is to ensure that this is as equitable and fair as we are entitled under the state laws. To get this process started, please send all your financial information to my lawyer at xxxxx. Thank you. Have a good week. -M
