Tell the secret in parts if she discloses one part you should avoid telling her the rest of the things. Or tell her something and ask her not to disclose that to any one if she discloses it then don't tell the secret to her.
besrfriendforever- trust the voice of experience. do NOT tell her anything! if you do, you can't blame anyone but yourself for the bad results, if you really didn't know, in your heart, whether you should or shouldn't tell her, that would be one thing. but since you asked, you must not trust her completely. if you tell things to people you know you can't trust, any bad that comes your way from it is what you already know will happen. so be smart and don't cause trouble for yourself. good luck.