I need advice!

I'm 16 and have grown up in a loving Christian family, but I have kept part of my past from so many people. When I was 6 and 7 years old my brother, who is 6 years older than me, sexually abused me multiple times. I didn't understand what was going on at the time but realized what happened when I was 9. I was so ashamed of myself and scared I never told my parents, or anyone. For a long time I really struggled with it. I felt so dirty, alone, worthless and just gross. I used to cry myself asleep every single night. Then I found a friend who had been rapped and she helped me so much. I have spent almost 5 years of my life shoving all the memories into the smallest darkest corner in my mind, trying to hide that part of myself from everyone except that one friend. And it worked, I hadn't thought about my past for a long time. But, I recently went to a church camp and it's become very clear to me that God is calling me to forgive my brother and to share my story to encourage girls that have been or are in my situation. And I really want to do that and share everything with these Jr. High girls, that I'm a small group leader for at my church, but I'm still so scared about what my parents will think or do to my brother or even to me for not telling them sooner. Someone please give me advise for what to do. I'm just so scared and feel so alone.