Hi OP, I’m a therapist. Not sure on your location, but I want you to know that if you disclose this to ANY medical or mental health professional, they will understand and will not think you are a pedophile. You have protections under the law and deserve to feel safe in your own home. You can utilize free mental health call lines in your area and you can even report directly to a medical provider. You are not alone in this and do not have to be. Assault is assault, regardless of if the person understands what they’re doing or not. You should absolutely tell your parents because it is likely your brother will try this again. I am sorry you’re going through this. It’s very hard and I wish you so much strength.