This girl is copying me and does not own up to what she does in general. What should I do?

[Maria]

Some background info: I have this group friends that I have known for going on 8 years now. There is this one girl that looks similar to me so everyone (mainly mutual friends) tie (almost compare) us together. I have done my best to overcome this situation. To be a friend and be open but all I get is more lip service, a more sneaky approach and a loss of faith in my valued friends.
She actually would burrow my clothes in high school then take pictures of herself IN THEM and post the pictures on facebook. She even started doing her makeup the same way as me in high school.
She is ultra-catty but claims to be unaware of anything that she does (even after we talked about it). She constantly says backhanded comments to me and acts oblivious. To make matters worse she started obsessively copying me (she started shopping at the same store as me, buys clothes as similar to mine as possible, buys jewelry like mine, seems to go on a hunt to mimic whatever I am wearing or into when she sees me).I tried to confront her about it in a nice way as a friend but she just took advantage of the situation. She would act genuine and say “I copy you b/c I am not creative like you” but then she would put in a little jab. It just all felt/feels like an act to me, her words portray one idea but her actions/body language reveal another. She would say things that a real friend would say but then she would put in some childish jab. I have come to expect two different people from her: 1. the person that she pretends to be around others and 2. the person that she only lets slip out when we are alone. She uses any little mistake that I have made against me.
I feel this huge sense of insecurity from her and desperation (but no one else other than my family sees it). I can tell that she is threatened by me being secure with myself and she tries to play it off to everyone. She even copies my sayings and ideas and conveys them to be her own. She is very showy and puts on a face to everyone that she knows or meets. When we hang out with our group of friends she does/says things to try and undermine me (almost like she is trying to damage my relationship with friends). During the conversation about her copying me she made an attempt to blackmail me. Her words were “if I was really after you.. I would tell your boyfriend about what you did with your ex”. I hadn’t done anything with my ex but her mere attempt was insulting. A real sincere friend would not say something like that.
She is so bad that she used to troll my facebook page daily/bi-daily, then be competitive on fb by posting something on a mutual friend’s wall after seeing that I posted on the friends wall. If I changed the layout or pictures on my fb she would do the same within a day. I have now made it where she is restricted (unable to see any of my new posts, status, or pictures). All reasons why I now avoid her. It just kills me that she is able to fool all of my close friends, which I greatly treasure and respect. I don’t understand how she is being so obvious, yet not one person calls her out on her actions.

Thank you for reading this far. Any advice?

[Ms. Alamin]

don;t worry..

[Robert]

Wow she sounds like a phsycho call the police,by the way your talking about her she sounds creepy and I think she immitates you because your a great person and she thinks shes not good enough and copys your actions.so to resolve this problem Slap Her in the face.No but really I think you should call the police and file a restraining or tell her parents and let them know that shes acting creepy and you dont feel safe around her.