Has anyone confronted the "OW".... 

I agree with trish: The OW isn't really the one you took vows with. It may seem as if she is the source of all your marital problems, but if your husband is going to continue to cheat, confronting the OW isn't likely to stop the cheating--she may step aside, but if his heart is set on it, he'll just find someone else. I tried confronting my ex's mistress, and for a week, I went into a psycho-jealous rage where I was calling her and wanting to know WHY,  When in fact it was my husband's responsibility to furnish the reasons behind why he strayed, not hers. And I never did find out why, I was immensely wounded (and still am), and I finally chalked it up to the realization that if he was going to continue to do this, and the OW is going to enable it, even though she knows he was married, then the two of them deserve eachother. I would not recommend confronting her--you will not find the answers you are seeking from her and will only end up retraumatizing yourself. If you want to work on your marriage, then focus on the work you and your hubby have to do to save your marriage. And maybe take solace in the fact that what comes around goes around: The OW will get what's coming to her. Best of luck, achiever!! My heart goes out to ya...

I'm sure you want a girl's view here but...

I confronted the "about to become OM" once to tell him to back off.  Although he wasn't the least bit impressed with any piece of my mind. 

When I discovered my ex's full blown emotional affair I begged and pleaded with her to make a full discloser of what it was.  I wanted to see the emails she sent him, etc.  That was, I guess in a sense, my way of "confronting" him.  I know now, that wasn't what I really needed.  All it would have done is caused more pain.  It happened.  That's all that mattered.  And if I were in her place, I wouldn't have opened up my emails either. 

 

What I really needed to move past it was her deep down, despirate, come to Jesus remorse.  Not an appology.  Not an excuse.  I needed to feel her heart bleeding right beside mine for the pain she had caused.  She didn't have it in her.  She was too busy justifing everything.  And although this guy was the lowest most unspeakable waste of body fat imaginable (you really can't imagine), venting my anger on him would have accomplished nothing for me.  If he had stood in front of me, I'd have probably just shook my head and walked away from him.

I think your desire to confront her is want psychologists would call "displaced" anger.  You don't want to blame your husband.  You don't want him to be responsible.  You want to love him.  Unfortunately you also need a target for your blame and anger and she's the obvious choice.  But hard as it is to accept, it did happen.  It doesn't matter how or who started it.  No one but your husband is responsible for the choices your husband made. 

I vented by writing my wife a letter.  It was brutal and raw and I bled into it everything I needed to say.  I also didn't have to worry about being arrested for going too far.

achiever
My ex cheated a lot and he was very good at hiding it. Home on time every night and the hours and pay always matched.
I will admit I confronted one of his women once. I did get a certain satisfaction out of it. She was my only friend in a small one block main street town miles from anywhere. It was to give her my opinion of what she had done to our friendship; not the affair with my husband.
I waited where they met to carpool and walked up to the car. I never said a word to her as I reached in the window and grabbed two handsful of her hair. I fully intended to pull her out of the car. It took my hubby to get me to turn loose. I had her hair still in my hands. She was the only one I ever confronted. They both got my opinion and my now ex got more careful in his cheating.
It didn't stop their affair until he got tired of her. Would I advise anyone else to do that; NO. It was a dumb stunt on my part. It was all over my work the next morning.
Confronting the OW is always a bad idea. It usually doesn't stop it and you end up hurting worse.
Really it takes two to cheat. Did she twist his arm and make him have an affair with her. In my experience with my ex the fault was with him and his need to feed his ego with other wormen. I always considered the OW a victim of his need to fill his ego as I also was a victim.
I have had passes made at me. I never took the man up on it because I had a comittment to my marriage. So who would you fault? The OW or the hubby who broke his comittment to his marriage.