how can i stay sane/ get him to back off/ be free from his evil guilt inducing clutches?

alright, be warned
i cant be bothered with punctuation and correct capitalization
today is a rant day
deal with it

so here is my problem: after my boyfriend and i broke up, i was pretty messed up about stuff. and it took a while to get back to my normal self. this guy who my friend went out with but dumped started talking to me. he helped me deal with all my issues, made me laugh, made me feel happy. we started talking the day after the break up, and he listened to me rave and rant for weeks. he helped me move on and was there and listened to things i didn't even tell my best friends about. and then he screwed it all up by falling for me.
at first i thought that was very sweet of him, and told him that i wasn't ready for anything. i told him it was like an ego boost, and he understood. but he never moved on. i expected him to like me for a bit, and then forget about it. he didnt. but since he had become my closest friend, i couldn't distance myself from him. then i introduced him to another friend of mine, and he said he might like her. i got a bit jealous and recklessly decided i like him. so we went out for a bit. but my mom talked to me and then i figured out it was not the best thing and broke it off.
he fell for my friend, and everything was good. she didnt want to have a relationship with him, though he persued her relentlessly. but then finally he got the message... the 2 of us were fine... until i had problems at home, and he found me having a breakdown. then he decided he was in love with me. and he meant it. i'm 17 and i know im not ready for that, and i have told him so. many times. but hw got this idea that we were meant to be together and wudnt stop mentioning how perfect it wud be if we were togther. for months this continued, though i tried to repell his advances. i feel like i owe him a lot since he was there for me when i really needed it. we were uber close, always around each other, always holding hands, always moving towards each other. i knew it was more than friendship, but thats how it had always been with us. and then i did the stupidest thing of my life and let him kiss me. for the record, i was starving, had been feeling really wierd all day and was conflicted. AND i told him i might regret it later. he said he didnt care. so even though it was real, the whole day felt like a dream. which is why we somehow ended up kissing. the entire weekend i thought about him. on sunday we went to see a movie. neither of us knew what was gonna happen. but we kissed again. he was really happy.. and it made me happy to see him that happy. but i mistook that for me feeling good about the whole thing. and then i started freaking out, and i knew i cudnt do this. so i broke it off with him. it was bad, i had never seen him that angry before.
but he went home. and then wrote to my other best friend- my exboyfriend and told him what happened. my ex told his other friend, and his gf- another friend of mine. soon the whole group found out. i wanted to forget it ever happened, and he refuses to forget it. so it was really awkard for a week or so. then we started talking again. but i kept my distance from him. the thing is, i really regret it and with it never happened. i feel immensely guilty about it, feel horrible and uncomfortable around him. i dont like being with him alone, because he invariably brings up what happened. he crowds me constantly, and refuses to believe i want nothing but friendship. the thing is, the reason stuff happened was i was confused. but now i know i dont feel the same way about him as i did about my ex. so there is no point to try to work out our 'relationship'. i just want a friend, and he doesnt understand the meaning of distance. so i stopped talking to him for a while. life was so much better! i felt less guilty, cud do what i wanted and was much happier. and then a mutual friend decided to hold an intervention. so now im talking to the kid again.
but its bringing me down. he wont stop touching me. he wont stop crowding me. he wont give me distance. he wont stop comparing my behavious with my ex who is my best friend. he wont stop asking questions:where are u goin? with whome? why? when will u be back? when will i see you? when will i talk to you? why is your hair up like that, you never had it like that before? why do you like dogs now, u always liked cats? why are you spending so much time with this guy? and he even got our gay friend to ask me to prom because he cant stand the thought of me with any guy. he follows me around school, follows me when i go to talk to my crush and breathes down my neck.
i am aware if i hadnt kissed him back, i would be so much happier right now. but as far as i am concerned, that never happened. he feels the need to know everything about me, analyze every new thing about me and challenge it. I cant stand it. if he touches me, my body involuntarily moves away. if he looks at me, i look away. he asks me questions and doesnt get a hint when i dont answer. I dont know how to save out friendship. nor am i sure i want to. being with him is physically painful. i dont want to be around him. i dont want to be in physical contact. i dont want to be interrogated.
and the worst thing is that he thinks of me as his only friend, the person who has made him social. and everytime i back off, he says things like he is feeling depressed and thinking suicidal thoughts. and i feel horribly guilty. but if i dont keep distance, how can i get my message across? I have talked to other friends to make sure he has someone to talk to. but i cant stand being guilted and feeling so rotten all the time. i need my space and my independance. i am not his wife, his property, or his in any way. and he doesnt get that. he talks about me all the time, even when i am RIGHT NEXT to him. and it drives me crazy. i have been nice about it, i have been an absolute bitch, i have been understanding, i have been aloof. but he doesnt get it. he is stuck in denial, has decided we are soulmates or something and refuses to see the truth. i have had my fill of this toxic relationship. i dont know how to deal with it anymore. i want my life back. i dont want a shadow that is constantly nagging and critiquing and guilting.its driving me insane. I am at wit's end! can someone, anyone PLEASE tell me what to do with him?