My best friend is a lier help me...?

Okie iv been friends with this girl for 3 years and the 3rd year she started lying to me and everyone im a shy person and don't like to confront ppl but at school i went to the consular im forced to see and told her that she put on my space that i hate Amy that ***** need to die and that on the phone she told this guy that she was going to slit my throat when im sleeping and im not scared of her or anything but i sleep with my window open at night and i could just see her their with a knife and she got in trouble and she went on saying to her EX bf that shes a vampire lived in Ireland her p[.parents got fryed because their vamps and she lived in a tree house in the forest and she was born in from a diffrent place and i told the consular that when she was in the room and the consular said are you thinking on missour? and shes said yeah i meant that and she lied to her face pissed me off and then my friends the 3 of us are in volleyball and the girl told my friend the same lie but her parents died in a care crash my mom was driving us home and i asked every one where they were from and my Friend blurted out that the girl was from ireland and my mom and i herd her whisper "shh she dosent know that" and i took her and that one Friend to a drive in movie and we confronted her she told her ex bf to hold her back so she don't go all vamp on us (was full moon) and we confronted her and she said well i meant oh i accidentally said etc. and shes copying me and saying things shes not on the internet and in real life and i hate when ppl lie and it makes me upset because of all the ppl shes lying to it breaks my heart idk how to handle this right now we are not friends but i know again we will. How can i confront her (rember im shy) and get her to stop?