The counseling was because of the affair?
Did he say why he was hiding so many things if there is nothing to discuss?
Are you still in counseling?
Is he still communicating with this woman?
Of course it would upset you. Your husband is talking with a woman 25 years younger than him who obviously is attracted to older men. He lied consistently and willfully to hide this fact from you, not because it would upset you, but because he didn't want to stop. Lets be clear here, he knew from day one that what he was doing was wrong, that's why he hid it. Saying that you would be upset is an understatement. There was something to it, and his denial of that concerns me even more than what he did. If he can't be honest about it, then he's most likely not fully committed to stopping.
Since he was in the wrong and the one being deceptive, then you should be able to discuss it and have your questions answered whether he thinks it's important or not. He was the one who deceived you. Even if he didn't become intimate with her, he lied. What was the reason for lying? WHat was the reason for talking to the woman at all? Taking her out to dinner? You deserve to know the answers to your questions, and he needs to ask himself why he did it in the first place, and most of all, will it happen again.
I welcome your thoughts, let me know if you want to talk more.