Dalila,

I don't know what your brother remembers. You could ask him and tell him that you are sorry. The last thing I want to do is minimize what a child goes through after sexual abuse (I was sexually abused maybe twice by a neighbor, in a pretty minor way, and I repressed the memory - remembered it sometime in my twenties). I also don't know how far it went. But from what you are describing, you have suffered from this a whole lot more than he probably has. He might not even remember it. And you were a victim too.

I am sorry that you hurt so much. Telling your T about it will allow her to help you, and you do deserve to feel better.

I don't know what religious background you have, but maybe confessing what happened to a religious authority would also allow you to move past it, as they could help you to complete the repentance process (it sounds like the only place where you are stuck there is letting go and forgiving yourself).

You aren't a bad person. You deserve to feel good about yourself and who you are now, and to have a happy future.