Please help. why is he doing this? why did i make such a bad desicion.?

theres this boy in my class. he is really bad. he steals, lies, cheats etc. about around christmas time last year, he stole a present that my teacher received, put it in his bag and said that it was his. he also gets teased, only because he does such bad things. he trips people, calls girls names, steals from the school store, and gets suspended alot. around novemebr, i sortof started to feel bad for him,. idk y but i just did. when it was close to thanksgiving, he asked me if i wanted to go out with him. i didnt like him and i never did like him, but me being stupid at the time and not listening to my self, i said yes, only because i felt bad for him. i told him not to tell anybody. two days later 3 people in my class know. a day later i broke up with him. i told him it was because i didnt like him, i only did it because i felt bad for him and he told people when i told him not to. a few days later a bunch of people in my class asked me if i went out with him. now let me remind you, he cheats, lies and steals and gets suspended on a regular. i kept saying no, when they asked me if i went out with him. it was too embarassing to say i did. it was the worst desicion ive ever made. today in school a boy asked me if i went out with him i was like no, i didnt. then he pulled me to the corner and told me that the boy that i went out with for about 2 days showed him the email. i told my parents and thanks to him, i cant go out with anyone till i'm 16/17 . alot of other boys have asked me out, but he has ruined their chance of them being able to go out with me. i like someone but i wont beable to go out with him because im not allowed to go out with anyone untill i am 16/17. this boy is really annoying and selfish. i dont know why i made such a bad desicion. what should i do or say to confront him, make him stop showing people the email, stop telling people he went out with me, because he litterally brags about going out with me. i just need help in this situation.