How do i stand up to my mom...?

My mom is always religious and hates any thing against it.... I cant even live my own life with out having to make up a lie that says im a freakin saint.... I want to date.... But she wont let me... I want to make my own disitions but i cant.... I corted with one boy i reallllly like and he likes me back.... But my mom read a letter i wrote to him saying that i cant wait to c him and stuff.... And she ended up flipping out at me and wont even let me c him any where any more.... She threatened to take my phone away... She yells at me every day and im reallly scared to say any thing back cause im scared she'd take every thing away.... I made a promise to my self that once my 16 birthday came im getting out of this hell whole.... I cant stand to even look at her any more with out that.... That.... Evil, threatening, face.... Im not good at some subjects at school and all she does is flip at me.... I just want to yell "PLEASE JUST STOP!! i want to love my own life and if theres consiquenses... Then ill live with them... I want to live my own life... Just leave me alone and let me live...." but i cant even think of doing that with out her just taking every thing away.... I live out in the contry which means i cant go any where.... I wanna c my friends..... But im not aloud to go any where with out her knowing... And even when i am in town.... She has to know every single place ive gone or am going to go..... Please some one help me..... Im beging....