She is the one pushing the "you better be 100% committed to this" and reconciliation. I would suggest that you call her on it. She is talking out of both sides of her mouth. You don't have to be mean about it..just practical. "W, I'm committed to us, but I honestly don't believe that you're ready. I want you to be sure you want to work on our marriage, and that includes breaking things off with OM, before coming back here." I think breaking things off with OM involves not going on this vacation with him. Do you honestly think she's ready for a R with you immediately after coming back from vacation with him? I can't imagine that this is strictly a plutonic thing. Guys don't usually keep taking women on vacation if they aren't putting out.
In the end, it's not the years in your life that count. It's the life in your years. Abraham Lincoln
It is hard to fail, but it is worse never to have tried to succeed. Theodore Roosevelt