Exposure doesn't guarantee the affair ends, but depending on who the affair is exposed to (like, for example, OP's spouse,), it may add some stress to the affair. Affairs typically flouish in secrecy so exposure could potentially have a negative impact. It deflates some of the fantasy. The feeling of two people secretly in their own little world.
Long term, I think a lot would depend on where the affair is, how strong the bonds are, are the people involved risk takers? What are the gains and losses? Where are needs being met? Even if the A ends, it doesn't mean that reconciliation will occur. It definitely provides opportunity, but other factors could hinder the opportunity (i.e. blame, fear, a lack of patience, etc...).
Regardless of how carefully and calmly it's done, exposure often provokes intense anger and elicits blame. More then likely it will initially be seen as hugely spiteful and revengeful. Motivations will be twisted to help validate choices.
There is no arriving, ever. It is all a continual becoming.
