Sexual harassment

So this is a long story but I want people to know about it. I am 14 and my mom has been dating a guy for about 4 years, he has a son that is 15, and me and him were really close and best friends. His name is Trevor. So trevor was staying at his moms for about 2 months then finally came back for the day. So we were just hanging in my room and we were both sitting on my bed like normal. All of a sudden he gets sexual asking me if I masturbate, if my bf ever fingered me, etc. It got very awkward and he kept asking me to have sex and I kept telling him no, then he wanted to finger me and I kept saying no to that also. The he blares music, gets on top of me and he is much stronger then me so I couldn’t get him off of me. I was wearing a romper and he was trying to get his hands in my pants and I don’t exactly remember if he felt my vagina because I was terrified and at the same time he was grabbing my boob. I told him to get off of me or in 3 seconds I was gonna scream. He got off of me and left to jerk off because he was horny. He told me he would pay me 300 dollars to let him finger me and 100 dollars to keep my mouth shut but as soon as he let I txted my bf and told him, and then I told my mom. I’m no longer able to see him and he denies everything that happened. I told my mom I didn’t want to go to the cops. And my bf has been very supportive and I’ve told my closest friends but I’m scared that when I get to school it’s gonna go around but then I also want it to, to show other girls to not be scared to tell someone if something happened and to warn other girls if my step brother. Thanks for reading and please leave me advise on what you would do down below.