Option 1: Don't respond at all. Have someone else call him after the birth to come in and see the baby and he sees her (the baby) without you. Total NC for a while.
Option 2: Respond in the same tone he wrote you. Also just as short. This keeps some consistency from the last time you saw him.
Option 3: Respond more positively. Could be considered the high road, but wrecks consistency. (Consistency from the last occurrence may NOT be what you're going for.)
My only advice would be whatever one you choose, stick with that for a good while. Know what I mean?
