Made into her Step-brother's Slut

I know what my step-sister has been doing with my step-dad since she moved back in. When she left I was just a kidd. She doesn't realize there are two men in this house. She is the first thing I ever jerked off over, and the way she has been walking around the house, half naked, it's just too much. She hasn't even seen me in the few days she has been back, she has no interest in her "kidd" step-brother, but I change that. I change everything...