People think I'm easy for doing something I didn't want to do?

So I'm a shy 15 year old, I don't have many friends anymore after arguments etc.. I wouldn't say I'm bullied, just lonely. This guy from my school takes advantage of this he says I don't know how to say no...(He's 17 and in sixth fom) He invited me out recently, and I agreed. We were walking down the street and he grabbed my bum, I wasn't too fussed then he lent in for a kiss, I tried to pull away but he held the back of my head still... he kept touching me where I didn't want to be touched and I told him I didn't like it, and kept asking him to stop, but he just smiled and carried on. He slid his hand down my pants and tried to finger me down some alley, I wriggled away and told him I didn't want it... He then said "Fine then, just let me finger you through your pants".. I said no, get off please.. Then he stopped, and sat on the floor, and told me to get on his lap, I refused but he just pulled me gently down onto him. He started kissing me again, and tried to take it out of my bra, I tried to tuck it back it but he wasn't letting me.. then we stood up and he took his out while he had his arms around me and told me to get on my knees... I kept saying, no i don't want to, I'm not going to. he just said "If you don't suck it ill force it up your a**, and you know I'll do it" He then pushed me down by my shoulders onto my knees, and admittedly I did it. I left feeling sick to my stomach and actually cried a few times, only to find out he told everyone I'd sucked him off down some alley, and how I was a slag and now everyone knows, and they hate me what can I do?