I dont know when its right to speak up

I recently got abused and raped by my foster dad and still dealing with it I did not speak up for 5 months and I finally decided to is it normal to feel as though you can not open up to the investagators fully because you are scared of what someone may say or do, it kinda complicated being in the system after loosing your parents to a drunk driver and then someone who is suppose to take care of you rapes you multiple time. I just dont have a support network besides my riding coach and my child protection worker I just dont know what to do.