I went through a similar sitch with my W. A few weeks after she announced her A (thinking that having it all in the open would make her feel less guilty which it did not)I decided to state my case for our m. I wrote her a letter telling her of my love for her and that I knew she was not open to us now but these are my dreams for our future etc. She loved it! Cried like a baby and told me how confused she was BUT a few weeks later she informed me that she wanted to go away with OP for 3 days (that didn't sound like confusion to me!), "Is that OK". My first thoughts were "are you insane, how the F could that be OK!" but I held back and instead said "Please don't ask me for permission because I can't give it to you but you are an adult and are free to choose what you wish to do" I let her go. I said "Have a safe trip" (No F'n way I'd say "Have a good time") She says they don't have sex and I believe that in day to day get togethers but going away together for 3 days sleeping in the same bed, give me a break! Anyway, my morals daid what she was doing was wrong, of course, and what your W is wanting to do is wrong too. Yet, do you want to take this stand now? Your W needs to know whether this fantasy she is living is real or not. If you don't allow her to go and do give the ultimatum (I almost told my W "If you go don't come back") be prepared for living hell. Only you can know whether this is the time to say "enough is enough woman" I chose to let her go and let her live with her own conscience afterwards. I also realize that you gave her an ultimatum earlier and now feel you can't back off. If, in your heart, you feel you need to back off then do so. Nothing (almost nothing) is irreparable. You can tell her you've thought long and hard and realize that she must do what she feels she must to resolve this situation. You can't give "permission" but you are man enough to let her make her own choice. It's tempting to keep her away from him but, bottom line is if she's gonna F around, she's going to one way or another. But what the HELL do I know. Anyway I will be thinking of you as you make this decision. It is a tough one. Keep us posted.
