Exactly what Heaven said above. I never once said a negative thing about my children's father in front of or to them. In time they made their own decision. My daughter is getting married in October, although her father will be attending she stated mom you raised me YOU will walk me down the aisle.
Kids know very early what is going on, what is right, what is wrong they do not need to be told. They can sense right from wrong. If you are happy they can sense that also. Try always to be positive when you are with your daughter.