Sounds good. I'm glad you understand what you are up against.
What she feels is "real", there is no way you will convince her against it. They will keep that going as long as possible.
I have found that a WAS WILL try to come back if they know you are with another, but it is to show that they have you.
The other side effect is being cheated on, is the cheater feels like they have "power" over you. It's mental, but you are being supportive while they are doormatting you, and it puts you in a slave position in their mind. It's not easy to get out of this position.
I'm telling you so that you know. The best thing you can do is GAL and be sociable and not be affected at all by the WAS. Many of us determined it was not even benefitial to "help" the WAS, let their affair partner do that!
