Breaking a taboo!! Stepbrother crosses a line

I just wanted to go on my live stream when my stepbrother was in my apartment. He told me no one was home and he was bored. I couldn’t do anything about his boredom. He pushed me onto the couch and made it clear to me that he wanted sex. I didn’t know how to react… I was shocked and spread my legs. Why can’t I resist him? He took me from the front and from behind. Then he pulled me in front of him and squirted all his sperm into my mouth. I just told him to leave my apartment. Have I crossed a line? Is what I’m doing to him still normal?