Almost raped

I was almost raped in a bar last year. I had a couple drinks, then a guy came up to me and we started talking. Later, he asked "Do you want to have sex?" and I said "yes". We went back to his place, got naked, I sucked him off, and just as he was about to place his penis in my vagina, I screamed "OMIGOD YOU SICK FUCK!" and called the cops. He's currently serving a 10 year prison sentence.

Almost raped? How is it rape when you agreed to have sex with him?
That makes no sense at all You agreed to have sex with him. Why should he be in prison because you backed out of it and called it a rape?