I had my marriage anulled after 4 months. The attorney forgot to change my name back on the paperwork.?

I assumed it was and went back to my original name. A year later, I was in court to finalize my son's adoption and found out that my name was NOT changed back. So I had to keep the idiot's name and my son had his last name also. Now, I want to go back and get it straightened out. I didn't think it would be that big of a deal at first, but it seems that it has become a problem now. As he has announced in his stupidity that my son has his last name... so he must have some rights for visitations or something even though he is not on the adoption or his birth certificate. This was done in July of 2009, and he is now trying to play games with our lives. How do I go about changing both of our names to my maiden name as it should be? Will I be paying thousands of dollars now? Thanks, need some help here