SA, I think you can do both. Don't contact him unless you absolutely have to about kids or finances. Let him contact you. When you do see him, act like you said - friendly, upbeat, and like you are fine. Keep it light. Let that be the you he always sees. I try, but it is hard with my H still living at home and he does see me on my bad days, too, though I try to keep it out of his face.
Act "as if" you are moving on with your life and are coping just fine. Eventually the acting becomes reality, which will benefit you no matter what happens.
