Again, haven't had a chance to read your whole sitch so I don't know all the particulars, but I guess you have two different approaches you could take.
IF OM is/has moved but she's still talking to him you could take a hard line and tell her you don't think it's appropriate that you vacation together while she's still involved with OM. It sends a wrong signal to your W that you're ok with the current living arrangements and her continued contact with OM. It can show her that you're strong, will not play second fiddle to OM and if she doesn't like it, too bad.
On the other hand (and this is what I did), my wife and I went to Disney two times while she was still hot and heavy in her affair (after I found out, there was another time prior to my finding out). One time it was just us and another time we took the kids. It was the hardest thing I ever did having a good time, showing no emotion, etc when she would sneak off to call or TM OM. You can, in affect, show her you're a better man than OM. Time you spend with your W in a family setting, WITHOUT PRESSURE, is good for you. If Disney is a special place to you and your W, it could bring back those good feelings from where you two started. Has your W given you any indication of the things about you that bother her? You really have to pay attention because a lot of times those signals can be buried in other conversations. If she has, taking a vacation together can be a great time to 'show' her you get it. But don't tell her any of that. She'll have to SEE it. And she won't believe it for a while.
I have to tell you. It will probably take a long time. But it can be done. Show her the man she fell in love with. Be her friend. But it's going to be hard. Hardest thing you've ever done.
I don't know what the right answer is. DB seems to suggest playing the wait it out game. Other sites take a harder approach. Both can work and both can fail. A lot can depend on what led to the EA/PA. If she's crying on the phone a lot, she's conflicted. And conflict is good for the home team.
What do YOU want to do? You know your W the best.
How long has this been going on? How long separated?
Hope4us
Me - 49, W 49 S22 & S18 Dday 9/4/07 W claims NC 4/7/08 8/29/09 - Divorce Busted. Lots to work through, but we're going to make it.