seeing this from the outside its easy for me to tell you this, let the mother in law go back home, then your wife will not have a partner/friend to rely on, you have to call the shots here, play her at her own game, the kids are young and will have no idea what is happening, remember its her that is not allowing you to have them so dont have them, its hard i know but play her she may even give the kids to you if she has no one to help, you have to be strong and hard on those that you love and those you hate, it will be sorted one day but not today, be strong