Do I have the right to sue and do I have a good chance to win the case(READ DETAIL BELOW)?

I have an uncle who has had custudy of my little brother for 2 years, and at the sametime time I'm working towards receving joint custudy of my little brother. A court appointed case worker visited our homes, to interview each person and view if each person's home environment is safe for my brother.As a tactic to avoid me from receving custudy my uncle stated to the case worker that, " I know that my nephew is GAY, and has made a tape." Well I did receive custudy, because his claims were false and never proven. So could I sue him for slander under pain and suffering.If so how would I go about suing him?