What constitutes a rape?

If you said no and he physically harmed you until you said yes that's rape. If he threatened you in any way to get you to have sex with him its rape. If no was the first answer and he guilted or harmed you into doing it it is still rape. File a police report pronto and talk to your parents. I would also suggest you talk to a psychiatrist, because you may be experiencing a stress disorder ( possibly ptsd). Good luck.