I exposed my H's affair....I then contacted the OW....even though the affair lasted a bit after that it fizzled quickly....OW didn't want to have to live with what I had told her....I was blindsided....had no clue that my H was unhappy....that he would even consider leaving us....I poured my heart out to her BEFORE I was able to confirm that they really had met/sex....my H then told me that he was considering marriage with her....well....I guess that didn't fly to well because pretty much after I burst her balloon....and she had to face that I was not an unloving, uncaring, cold hearted wife but that I really and truly loved him, the affair didn't seem so right....she actually said in tears, "I am feeling guilty and I haven't even done anything."....well that was a lie because they had slept together.....but she did feel guilty and I think that quenched the flame enough that she decided it wasn't worth pursueing...
I realize I probably got of easy with his OW....it was still well over a year before he returned to our town and began reconnecting with me....which was good....because I didn't feel like he came back to me because it failed with her....he returned because he wanted his family....including me back.....
I think all situations are different....but for me when my H had an EA and PA....both times I made personal contact with the OW....both times it killed the whole mess....