1)You will have to inform the various social sites and ask them to take down the fakes
2)if you want to continue with instagram you will have to adjust your privacy settings and then disconnect your Instagram account from any other linked accounts as even if you set your privacy settings high your details can still be viewed from other linked accounts. Instagram actually ‘warns’ for this to happen in their privacy settings:
“If someone with a private profile shares a photo or video to a social network (like Twitter, Facebook, Foursquare and so on) using Instagram, the image will be visible on that network and the permalink will be active. In other words, the photo will be publicly accessible by anyone who has access to its direct link/URL.”
3) Inform the police if needed,
4) confront the person, if necessary take someone with you to help.