Should i tell my friend im bisexual?

im 15 years old and a month ago i told my mom and a few friends who are extremely close to me however i haven't told one of my friends since she is only 12 and kind of young when i talked about the subject with her about homosexuality she showed signs of fear and disgust shes a very nice girl and i want her to know that we are just friends and nothing else so whats your advice