Im scared and i dont know what to do...

so back then when i was still in 6th grade i had friend with the name Cindy and she had an uncle named Billy (im not really sure if its his true name) but Cindy added me online and it was ok for me she was my classmate after all, but then one day she started chatting wierd stuff like shes saying "i just saw a mans private part" and at first i was confused why did she say that to me but then she asked if i wanted to see it i said no but she was insisting, then she chatted i'll show you but first show me your privates to" and that time i knew it wasnt Cindy cuz why would she ask another girl that, then she started calling me and i kept declining i was scared i was doing my homework that time i tried to change the subject but no, and the next day at school i talked to Cindy about this and she said it was her uncle and her uncle logged in to her account and used it to chat with me she also said that her uncle has been doing the same things to her other friends that were girls. I was freaked out and i wanted to tell my mom but i was also scared and i dont know so i started telling this to my trusted friends and they said to tell it to my mom, when i got home back from school one day a month passed since that incident happened my mom started acting wierd and it was because she saw the chats of me anf my trusted friend and she also went to my chats with Cindy she asked me why i didnt tell her this sooner i said i was scared. I really was confused about what else happened with my mom but i know she went to the police station to talk about this even printed my convo with Cindy but the police didnt care and even defended Cindy's uncle my teacher got involved and my step father and mother visited Cindy at school to have a private conversation with her and Cindy came back crying Cindy was my friend and seeing her cry like this i kindve blamed myself....now im at 7th grade and when i was at school about to go home someone added me on the blue app named Billy and had no profile picture but we have a mutual friend Cindy, it was very foolish of me to accept the request but when i did he chatted me a random sticker and asked me where im from i answered sarcastically saying i was from earth, then he suddenly sent a picture of his privates i didnt know what to do i panicked i was scared so i saved the photo for proof and when i was about to take a screenshot of our convo he deleted the message i was so anxious and i still wasnt home that time i wanted to cry cuz WHAT JUST HAPPENED (many other incidents like this happened to me so uhm) and when i was walking to my door i tried my best to not cry and act normal and i did i forced that smile even tho i just want to hug my mom to tell her but again i was scared, thankfully my aunt was there i asked her to come with me to buy something at a nearby store but i really wanted to tell her what happened already she didnt want to until i chatted her saying i really need to tell you something and she agreed, while we were walking i gathered up the courage to tell her and i did and she was shocked? She suggested to tell my mom and i said later when my mom isnt mad at her later that night i was doing my assignment and that guy called my blood ran cold i realized it was the same guy that chatted me back then when i was 6th grade that time I REALLY wanted to cry i was scared so i told my mom se instantly got mad and asked why i didnt tell her earlier why i accepted the friend request she looked through my convo with him i showed her the photo and then all i could remember was she was mad i was scared she answered the phone call the guy asked if i wanted money and asked to see my face....i dont know what else to say but until now i get getting friend requests from random persons and they kept calling me and im very scared....thats all sorry if wrong grammar or the way i explained it was confusing hehe...thats all thank you for hearing me out!.