I am really saddened to hear that you associated your sexuality with not being "normal". There is nothing wrong with being the way you are. Think of sexuality as a scale. Totally straight on one end and totally gay on the other. You can be anywhere on this scale, depending on your preferences. I, for example, am somewhere in the middle with my preferences leaning both ways.

I feel the main conflict here is associating your sexuality with the abuse you suffered by your brother. Maybe seeking the help of a therapist specializing in sexual abuse is what you should do.