How do I tell my bestfriend I have feelings for her

So I have known my bestfriend genesis for about 5 years now . And we are both bisexual I have never been able to tell her l have feelings for . It was rlly awkward when I had a sex dream about her the worst part is I am only 12 years old. I am scared to tell her I have feelings for her because I do not want to ruin our friendship . PLEASE PLEASE HELP ME