FIB, Are you keeping a daily journal documenting all this? You need to show beyond a doubt a history that you are actively involved with your kids lives and school. Have on your finger tips details of their teachers, medical history, extra-curricular activities, etc. Go talk to the teachers, other parents, etc. You don't want to be defeatist in any of this. Your W is doing to accused, finger-point, manipulate, etc for a while to come.
