My Divorce is not finalized! From 2000!?

The man that was doing everything for me said all was good and I did not have to do anything else because we were not fighting for custody or alimony or anything Just the DIVORCE but now I am told it is in default due to some stupid pay check stubs!.. I want my ex out of our lifes I want FULL custody of my kids because I have a special need child and my ex is dangerous and I can not afford anything!! I am having some health problems and if anything happened to me I DO NOT want him to have my babies. My special need son will end up serious hurt or DEAD! Can I sue this guy who originaly did this for me? He said this would not happen! It was suppose to be easy! What can I do and do quikly? Please help!