My Stepfather molested me! now he's working with kids ! What should I do ?

When I was 14 my ex-stepfather molested me and raped and molested my then 8 yr. old sister. I told my biological father and he immediately called cps and had them come to my school to talk to me. But being the scared kid I was I lied and said he didn't touch us. Now 20 yrs. later my mom and dad have both passed away, I found out he's working as some sort of teacher at a middle school! what should I do if anything? Or can I do anything? Are there any legal ramifications or could I be charged with slander if I told this to cps, the school, etc ? I just don't want it to be on my conscience if he rapes or molests a kid at this middle school.