Did she say how and where she met the OM?

Usually these "Soulmates" are Co-workers, mutual friends, or neighbors!! Out of 6 Billion people in this world!!

Is there anyway you can apply pressure on him??

Otherwise, yeah it seems that exposure hurts her and may feel like it will make it hard for her to come back....but thats not true. It depends on the character of the wayward and the untold truth of your marriage and whhat type of husband you were.