What should I do?

So I'm 15 and a virgin and I've been talking to this guy who's 17 and everything between us is like strictly sexual, we haven't done anything physical but like pics and stuff. And he's been saying some stuff that has me worried. He says he wants to make me his new "cum slut" and that I'll do what he says and that he wants to bring like 3 of his friends to... do stuff. He also tells me not to tell anyone about anything. He's a very well known/liked guy at school and I don't want him to hate me if I say no. And everything just feels wrong idk. (I posted this in another group too I'm just trying to get more opinions)