Mdu, I understand where you're coming from about H's feelings towards OW. As mentioned several threads ago, you have a circle around you and you alone set the criteria for entrance into your circle. You're not comfortable with your husband having feelings towards OW while trying to reconcile your marriage and I respect that.
I have to congratulate your husband on sharing this information with you though. He could have, and previously would have, kept this to himself. Instead, he chose to answer the question honestly and did so knowing that you wouldn't like the answer but that transparency was important to you. Sure, it wasn't voluntary and you had to ask but from what you've described of your husband since day 1, about needing gentle prodding, this feels like progress to me.
How did you respond to this information in front of him? Did you keep yourself together or go off at him? As Maybell alluded to, your situation is still relatively young and you have responded amazingly well to the curveballs that have been thrown your way. I understand the need to reinforce your circle in light of this information. Suggesting that you may be done however may be premature. Have faith in your husband and yourself.
Me: 31, W: 29 T: 4 M: 2 Kids: 3 (SS: 7, SD: 4, D: 3) Separated, still living together: Nov 2013 Separate bedrooms: Feb 2014 W working away; kids with me: Nov 2014