I have 2 kids and I am still married to my kids dad but we are not together.?

Me and that guy have been separated for 2 1/2 years.He has abandoned us twice and I had to end it.He has not supported them for the last 4 years ,I have and he also has not payed child support that was ordered by the court.The child support center acts as if they are in his favor of him not supporting these kids.I want to file for a divorce but I cannot afford it at all.I tried the Community Legal Clinic and the attorney said that we have to agree on everything.I don't even know the whereabouts of this man.What can I do I really need advice.I know someone out there has been through what I am going through.I wan this nightmare to be over ASAP.I know that he will not agree with me on anything cause he is very childish and most likel will use these kids as a weapon to try to hurt me likewise.NO NEGATIVE REMARKS PLEASE!