I think you've done all the right things so far, and I was pleased to see what a firm (but still loving/forgiving) stand you took with him. In my experience, that usually works best, and did for me as well.
Would your husband agree to MC? I think a good marriage counselor, specifically trained in dealing with infidelity, would be very beneficial for you two at this critical stage. Your husband is showing all the right signs (remorse, transparency, etc.), but these are still rough waters to traverse.
His breaking up with OW (assuming he is telling you the truth) is still very recent, and he's going to go thru actual WITHDRAWAL from her, as disgusting as that may sound to you. "Hard withdrawal" usually takes 2-3 weeks or so, and total withdrawal can take up to 6 months or longer. It's a brain chemical/endorphine thing (PEAs they are called). It's why he's still extremely vulnerable to any re-attraction to OW right now.
Do you have any form of intel that he does NOT know about, that you can use to "trust -- but verify" ??
