Was I raped by my step brother?

You said no and he didn't stop? First thats kinda weird you two are now family. I would be worried about if he got you knocked up or something. I would tell your parents thats wrong and he has a girlfriend? I feel sorry for that girlfriend. It was rape you said no that means noa dn to stop it. If you liked it and you don't wanna get him in trouble then don't tell but if you said no he should have listened. I say just talk to him and tell him next time to learn that no means to stop it.