i don't think you are an abuser. You were someone who was abused, didn't know that it was wrong, and then acted out on your sister. In a perfect world, none of this would have ever happened, but you are willing to admit that what you did to your sister wasn't right and you're so very remorseful. I think it would be a good idea to talk to your sister. Could you say something like "do you remember those games we used to play?" I think that you could both heal together. I think that if your sister is affected in any way, then she will likely be forgiving to you as she'll see that you were a victim, too, and you never meant to hurt her.