Talking respectfully about ex spouse in front of children

Hello Sara, I was listening to CBC radio the other day and heard your discussion on divorce. I am recently separated and my ex is very angry, bitter and does not say nice things about me in front of our 10 yr old daughter. I make a conscious effort not to do this about her dad, however he did it even before we separated. My question to you is what would you recommend I do in this situation? Also what book could you recommend? I really enjoyed listening to the radio program although I did not catch it from the beginning. Thank you for your assistance.