How can I legally deal with the blackmailer?

One of the girl or a gang I don't know but sent me a video in which she is showing my insta account and some of our lustful talks. At the end of the video only a small part jerking is showing also the girls is showing nudes. But my face is not seen. Now she is telling me that she will forward the video to my friends on insta well I have informed all my followers and reported the account on Instagram. Please advice