Wendy, My take on speaking to the OW about backing off. I would suggest that you not say anything to her at this time. The more your h pulls away, the harder she is going to try to such him back in. If you were to say something to her, that would a challenge to her to prove you wrong. The best advice is stay the course that you are currently on, carrot cake and all, and not say anything to her.
Wendy, sit quietly and the answers will come to you.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.