My sitch changed drastically once my W's affair was known by her family... In fact, not much changed at all until it was in the open...affair's thrive in secrecy. Once they are brought to light they lose a lot of their excitement.
Will confirming that she is NOT having an affair change the reality that your W still wants S right now?
Nope, it won't change reality, but it sure helped me get over my W knowing that their was an external influence that was affecting her actions.
in my case... It did allow me to let it go once I didn't have to worry about it anymore...I honestly didn't mind that my W had moved on... I was just completely sick of the lies... In reality it is THEIR problem, they have to live with their choices.