I NEED help MAJOR friendship prob and u cud save my ***!?

I told a friend a VERY VERY privete personal secret (i don't mean something stupid like who i fancy or wateva) she belived me at first then she don't belive me no more (i don't know y) but she told me i was bu*lshitin and lyin, (i'm not tho) and she said to me on the phone she wants me chinned. I told my cousin and she don't really no much bout wats happenin and i really don't want to her 2 hate me cuz she's my cousin and i love her. The other gir don't go to my school but i used 2 see her out of school and wants 2 tell every1 at my school wat i've apprently been lyin bout and i don't ANY1 knowin cuz it's a VERY personal secret and i don't want my mom knowin the secret. I have sort of talked 2 my cousin at school and she said she will always still love me but she don't know nothin much. I don't want 2 get chinned, every1 at school knowin and my cousin 2 hate me!! wat sud i do people??? xx i wud b greatful 4 answers. :D x