Hello Lady_Stardust, can I welcome you to the forums, and I'm so sorry that no one has replied as yet, as you would have hoped that you had someone speak to you.
It's an awfully long time for something like an assault to keep to yourself because of all the negatives thoughts that may have been circling around you, even though you pretended that everything was OK, but it has affected your life and maybe in the result in keeping them hidden away as well.
You are brave in doing this and I applaud you, now you will need help and guidance to show that someone doing this to you is illegal.
The weight of holding this secret was just getting heavier for you and you couldn't run from it anymore.
Are you able to write down on a piece of paper of what did happen, one document for your therapist and then another one for your parents, I only say this because there maybe things you don't or can't say to your parents, the best part is you are telling them.
Lady_Stardust please take your time, because it may require a change in your life, but we are here for you and always will be along this journey.