It is unlikely a judge will allow you to take custody of the children, unless the father is in prison or has other serious problems that would prevent him from parenting the children. Unfortunately, he can also keep you from seeing the children if he remains their sole legal conservator. If the father does have serious problems, it is possible that the District Court Judge in your area might grant you some rights as a conservator if he or she believes it is in the childrens' best interest. You should speak to a family-law attorney about your specific situation before making a decision.
Agree. You'll need to see a family law attorney. The natural father is also the natural guardian for his children, and is entitled to custody, unelss a divorce decree or some other proceeding terminated his parental rights.