I am not so sure she will not contact and expose him to his wife, she is thinking about it, I would guess. In her mind she may be thinking, if she knew, she would leave him, and then he would come to me, and we would live happily ever after. Watch out.
As far as what to do now, I agree with all of the boundries that have been offered, but I just do not understand her uncontrollable behavior when she is the one voluntarilly leaving the family bed. It is her choice, I would make her fully aware that she is more than welcomed in "our" bed.
