If a spouse really wants to leave they are going to leave regardless of exposure or not. (Although... my husband was dead set on leaving and paid 20K to D me!!! And then stopped it...)
I agree that everyone's situation is different, but I personally felt there was positives for me in exposing the affair and never thought twice about it.
For one, I didn't like the idea that he was telling everyone he was D me because "we didn't get along" or some other nonsense. (Yes, the marriage was not perfect, but everything escalted with the A, and until I had proof of the A, I didn't realize he was "baiting me" to make things worse and validate this decision).
The next reason, and this I felt was more important, by setting off the bomb I felt I was "getting it out of the way." I knew if I didn't set it off, it would just be this big elephant in the room. And it might even just build up larger. There would just be this big ugly secret.
So... I exploded it. Yes, and it was REALLY bad. My H was incredibly furious and it was super ugly. That night I jammed a chair in the door and the next day I was so paranoid I had the locks changed. I refused to see him for days because I was afraid he might kill me. Seriously.... but eventually he calmed down. Exposing it didn't stop the A, but it got the elephant out of the room. I felt it got some of the ugliness out, and allowed us to look at the situation with more clarity and move on. Quite honestly, I can't imagine not exposing it and how uncomfortable that would be. Just sitting on this huge secret. It just would feel so "unresolved"...
Also, once it was exposed no one had to worry about the response. It happened, everyone responded in their own way, and in time things settled. I felt it was much easier to move forward this way. I even think it made it easier for me to begin developing a friendship with him. He wouldn't have to worry about me having some secret I could expose or hold over his head. And this forced him to look at what he was doing, how others would respond, and deal with it.
There is no arriving, ever. It is all a continual becoming.