Of course some days are harder, it's no fun the road you are on right now...and no one, not one of us, could blame you for reading him the riot act. It just wouldn't accomplish anything...so try to hang in there and keep your head about you k?
Try to remember...you're a class act and behave that way, it's a whole lot more attractive than losing it.
My guess is since he wouldn't answer your question...he is still in contact with OW. Others on here may say..."don't jump to that conclusion"...but it's been my experience when you ask someone a question that is that simple to answer and they don't answer it. It's not good.
Next time you ask him that question and he doesn't answer you...very calmly tell him something along the lines of "I am going to take your lack of response as you are still in contact with her and that's not acceptable." Remind him that he agreed to go to a C with you and as long as she's in the picture he's not giving counseling or your M a real shot. Leave it at that, don't harp on it...just say your piece and drop it...calmly.
So...while all of this is going on in your M what are you doing to take care of you? What are you doing to try to keep yourself going, keep your spirits up....take care of Confused?