Oh boy, hopeful, I'm sorry this is happening. From what I read, this is what I'm guessing is going on: He is having an affair, and has been for awhile (probably with that lady at work). He is trying to get things all nice before divorcing you. He has separated from you (making it "ok" to date in his mind), and has talked to others about divorce (knows you have to be separated a year). He told you about this OW in case you hear something from someone else. I'm sure OW wants to be more "open" now to see his commitment to her.
He's scared, though. He doesn't want anyone to know about his "secret". It is an affair.
I can give you advice based on my own experience as being the one that had the affair. The only way my H could have stopped me and had me work on the marriage at that point would be to tell me that if he found out I was having an affair while separated that he would tell my family and others. And, if he thought I was having an affair (like you do with your H), he would give me the choice : COme home and work on the marriage, or he would not lie to anyone and that means he would tell others what he believes to be going on. He would have also had to reassure me that there was help out there, and that there would be changes. He would have had to tell me that there was Retrouvaille, counselors, and books. Also, getting people from my church involved would have stopped me as well.
Right now he believes he doesn't love you, and until he realizes what is going on with himself (by reading books, etc.) he will continue to believe this. While being with the OW, those beginning "in love" feelings will kick in all the time and cause him to truly believe it more and more.
He cannot work on the marriage with you while being with an OW. That's the bottom line.
The other option would be to let him "play it out", have his cake and eat it too, and let his conscience hopefully prevail. Hope that he sees what this "relationship" with the OW really is, and see what he is missing without you. Problem is, if he is with the OW it could take a longgggg time to see those things. For me, it kind of happened this last way, and it took about 3 years off and on.
