If you have clear proof that the affair with the OM is still going on than I would stop your kids from associating with his kids except at school. Time for you to put your foot down and demand that she either put you and her marriage on a higher priority or face the consequences of divorce. Remember she has a lot to loose if this happens. If she considers this man to be her soulmate and wants to be with him than tell her that you will let her go but without the primary custody of the children. In other words, she has made the choice of having the affair it will be up to her to face the consequences. Don't let her walk all your like a door mat. She will only make it worse for you.