It's easy to report such offenses to the police or right authorities when it's an outsider, but what if the offender is a family member and the family wants to keep this as a secret?
If you want to get out of that situation and be sure you'll be safe, you need to call CPS if you are a minor. Do that with a trustworthy adult, like an aunt, an uncle, a teacher or whoever you fully trust. You don't have to battle this alone.