You aren't forcing him to go by setting boundaries on how/when you will communicate with him. Ignore his whining. It is his choice whether to go to C. I would address it in C though -- that is, voice your boundary, your concern about his "forcing" talk, and him trying to fight with you.
And, keep it mind, he probably has to tell himself and OW that you are forcing him so that she doesn't get pissed. So, again, just ignore it. He's a big boy, you can't force him to do things.
