BG-I will say this. You are way to invested in making him happy. Amy has been a great mouth piece today and she is dolling out the exact things I would have said. You need to take care of you. What he does is what he does. Unfortunately, his history has shown you that he will do whatever he wants, no matter what he says to you. Who cares if OW loves him, he hasn't been faithful to either of you so if he goes to her, then she will learn that lesson the hard way and you will be able to move forward. If he stays, if you allow him to stay, the boundaries are set and that is it. The consequences have to be enforced as well (unless some EXTRAORDINARY circumstance were to occur). So you can't say he is breaking the rules already and then not follow through. Or he will continue to walk all over you.
Unless you feel the information is needed to make a choice, who cares what, when, etc... You already knew they were both liars. So BG, what do you want? What do you really want? You need to make that decision first. For BG, not for H or anyone else. Then you begin the work. Love you.
If you focus on the past, you ruin the future. You can only live for today.