Hi.
Sometimes kids, even relatives, close in age experiment with each other as they are trying to figure things out sexually, but this does not sound like a mutual exploration. It sounds like your brother was manipulating you into doing things you didn't want to do. It was great that you had the courage to say "Enough!"
Examining what you need psychologically will help you determine which path to take next.
People are usually confused and need to heal after having such experiences. Speak with a school counselor who may be able to point out local resources for supportive therapy. The only catch is that your parents will probably need to intervene if you decide to seek mental health treatment, since they usually have to pay for the services or make arrangements for insurance to cover therapy.
Your instinct seems to be saying "Don't tell them," though. Since you've put an end to your brother's behavior, you may feel there is no urgent need to say anything. Your apprehension about telling your parents may also stem from a fear they will blame you--and you may be right. One thing to think about when considering what to do is that you were very young when this occurred and you bear no responsibility for your brother's actions.
Maybe what you really want is an apology from your brother and an acknowledgement that what he did was wrong. If so, it may suffice for you to confront your brother and let him know how his behavior affected you. But be prepared: the conversation may not go over easily with him. He's likely to be defensive and even offensive toward you.
Good luck.
