How do I get child support to help me with my divorce?

I have been married since 1995 and I separated from my husband for 2 and 1/2 yrs. I have a daughter (5) from the marriage and I son from b4 who he helped raise from 2 to 16.When I requested a divorce they said I needed a child support order for the divorce to go smoothly, then when the court found out the kids receive public istance they stated that the state would take him to court but they never did,and now their dragging their feet . I want out... how can i get them to help. Please be aware that I have also went to the child support offices with info on him and his whereabouts and they said they couldn't take my info.