Don't despair. This is actually forward movement. I know it doesn't feel like it now, but you've just taken a leap of faith of sorts. You could have just accepted the status quo.
And I'm sure a part of you feels some relief in knowing that it was the om that was distracting your W and not her lack of interest in you. I don't know what your W's feelings are for the om, but I would suggest they are not really love. If she loved him, she would not still be home with you. She's probably clinging to him as a backup, a safety net of sorts.
I know there was much discussion of implementing a no contact rule. I would say that is a waste of time. She didn't consult you when she started the A, why would she ask your permission now. If you make it an issue it is only likely going to make her want to see him more. Eventually, she will grow tired of him, and end contact on her own.
We'll miss you but going dark from these boards is probably a good thing too. I go dark here myself from time to time. As much as a support as everyone here is for me, sometimes, it just makes me dwell on thing too much.
So, if you're lurking, my advice for you is this: Take some time to sort out your feelings, but don't let them consume you. And please, please, take some time and do something nice for yourself--something that makes you happy.
In the dark days to come, remember that your W does love you. Repairing a M is scary business. I know you want to protect your W but you have to let her fall a little or she may never realize how much she loves you.