yes no. or leave me behind?

so there is this guy we will call him sam. so i come back from winter break and i learn from three people that sam likes me but sam dated my friend lets call her summer and sam broke up with summer after about three weeks? well he broke up with her for no reason and before they went out he asked "out" another one of my friends lets call her Kat and she said no and they left on bad terms. then i hear that sam might ask me out and right now i am very confused about what i should do. so i talk to a lot of people about it and everyone says i shouldn't date him except for two people and i asked a lot of people! so i think about the pro's and con's of dating him i have never had a boyfriend or kissed anyone or had sex or ever been asked "out" so i am very new to this. i decide that i can not date someone i hardly know so thats what i tell people. and he finds out so he starts talking to me more and more. he sits next to me every day in math class always is looking at me in p.e. like a shark and i am really turned off by this.
so i don't want to date him. if he ask's me then i am going to say no.

i tell my close friends only that i would say no if he did ask me and i tell them not to say anything to him about this because i need to tell him. i know this is high school but that does not mean that i need to act like a high schooler right?

so he is still all over me for the next couple of days and then it all stops i notice he is looking at me less and i know right away that someone told him but who i only told my friends right. wrong!

turns out one of them told and now he doesn't sit next to me at all in math sometimes he doesn't even come to math class anymore whats the deal? is this a mind game or something?
because i can't deal with it!
i have to know what happened to make him act this way.
because honestly i am starting to like him and thats not a good thing. i need to stop right now! what do i do?