Tough spot for you...sorry you have to go through it. I am a teacher and see these things everyday. #1...make sure kids know how much you love them. Not through actions etc--Tell them! #2..can you meet with ex and swallow your temper and pride and politely ask/tell her what you see. Tell her how much you love your kids, that you love them as much as she does. But you sense an anger and disdain from them that you feel comes from her. Tell her she can hate you all she wants but BEG her to not throw you under the bus to the kids. You are their father and you want to have a healthy relationship. Tell her that their attitudes hurt you. Explain and explain again that being positive about each other is very beneficial to a child's well being. This partnership in positive workings aids in the overall mental health and well being of children. Be very forth write and ask her to understand and help. If she can't see the light...I don't know what to tell you from there. As I mentioned, I see this everyday. Take a deep breath and go talk to her without anger. I hope you can work it out.