Need help

I was curious if anyone knows about Family Law in South Carolina. My Hopefully soon to be ex put his name on the birth certificate after my son was born, knowing that the child was not his. He stayed true and supportive until about a year ago. (I guess he figured we aren't together any more so why bother with a son that is not really his!)My son's real father has been showing interest for the past few years and wants to be acknowledged as my sons father. Do I need the cooperation of my soon to be ex(which would be hard since I have not seen or heard from him on over a year)or could paternity test results showing that my ex is not my sons father be enough to allow us to have my sons birth certificate and name changed? I know this will be a long process I just need to know what the law is and where I should start.

Thanks in advance,
Missy

South Carolina