"But I'm Not Mad At Daddy"

As mothers you want to protect your children. You try your best to raise and provide for your children using your best judgement. Often times what's best for you overrides what may be best for your kids. 
They say its nothing like when a woman is scorned, but who pays for it? The children. Unless the father of your children are extremely violent or cannot be trusted, let the children determine whether they want a relationship with their dad or not. Don't speak negatively to your children about their dad. 
 Allow your children the opportunity to know who their fathers are whether he's mean,cheap,funny,quiet or immature. Just because your relationship didn't work out, doesn't mean your ex can't be a good father to his children.