I think my ex friend might have "done stuff" to her little siblings. HELP?

[Georgia]

So I had this friend, but she left my school at the end of yr 8. Im going to yr 9 very soon. But a few days after she left, I was talking to her friends, which are my friends, and they asked me if i can keep a secret. I said yes. Then one of them said to me that my friend molested her little brother and sister. Now I don't know if this is true. I am not in any contact with my old friend, she hasn't got Facebook, twitter etc.. I haven't got her number or her BBM pin. What can I do because it is serious? I wouldn't like to say I was friends with a child molester. It's freaking me out I am actually have nightmares about it.

[Rachel]

First u need to be sure before u bring it to someones attention. Have to get facts straight, if ur having nightmares talj to psychologist

[Zoey]

Go to the cops.