I only read some of your back situation, so I can't tell if W is in counseling or not. It seems if W agreed to go to individual counseling to discuss emotional affair and other issues on her own maybe you would feel more safe if you had to take a job elsewhere for awhile. These fantasy relationships seem to indicate people need to work on some individual and self esteem issues at times, right? Even if you fix your marriage and your R is perfect, she might still have mood or self esteem issues that she seeks to solve in that way if she doesn't take a good long look at herself, which you can't make her do. Now might not be the best time to bring it up either.
All I can say is be careful not to get in a big fight tonight. Seems emotions will be running so high you may have to set some time out ground rules or other tools in place for the big discussion. Can you have a somewhat time limited discussion in a public place? Sometimes that can help things from escalating.
