Your H.... what a fool! But you knew that OW#1 was but a symptom of something worse. Granted, she didn't have to be a willing accomplice, but your H is the chief culprit. I am so sorry.
And no, you don't owe him "friendly", just "congenial" -- and only for the sake of your DD's. He is nobody's friend -- not even his own.
One day God's going to lead you to someone who truly values you for the wonderful woman you are. A decent guy who will treat you right. In that I have faith.