Like I said before....she wants you to be "ok" with her leaving and to be her friend and make it "all ok". She wants you to get to the point she is so that it isn't HER leaving but you BOTH feel it is for the best and look, seee....we are still friends everyone???!!!!
I think you are right to do something. Someday, you will be coparents together if she leaves, but you will never just be friends. Do something now. Do not make this easy for her to leave. Make her see what she is doing. She cries at church, she cries when her kids say stuff, she KNOWS it is wrong......There is NO REASON for her to not TRY without the OM in the picture....her family and kids deserve this...a real try with counseling, retrouvaille, etc. YOu have told her this, but tell her again. If after x amount of time, nothing has changed....after NC with OM (full transparency to you), books, counseling, retrouvaille, then you both can say you tried and call it quits. There is No reason she can't do this!!!!!