i need a lawyer to amend my divorce decree, he stated he had no children and he has two.. and lied and gave me false information

I left my husband five years ago. He filed for divorce 2014, and stated abandonment, which the truth is, I had to leave with my children due to domestic violence..and because of his addictions. He mailed me some courts papers which I contested the divorce but to my amazement, i just found out that he intentionally gave me the wrong index# so i send the papers and they never got it..i do have the accurate index number now... He also told the judge that he had someone serve me the papers and that I lived in NYC at the time, and that I sign the papers, and I don't even know this person, and haven't lived in NYC since 2012.. I moved to P.A. I went for child support now, and because what it states in the divorce decree i have to amend the decree... He lied that he didn't have children so he won't have pay child support and always threaten me if i file.. He also has a pension, and we were married for 29yrs