As far as I know they are still seeing each other. OW kicked out OM and he is getting a place of his own. Talking with my therapist and another counselor, they said counseling can work if the affair is still on going initially, but will eventually fail (obviously) if it is not cut off by the 3 or 4th session or so.
My initial reaction was no counseling while it is ongoing, my only hesitation is what my therapist said, and the fact that this would involve individual counseling for her which hopefully will make her realize how rash and crazy this whole thing is. As of yet, she has not spoken with anyone about the affair and this guy except with him and her mom. Despite a swath of people knowing, she refuses to discuss it with them.