can i just get some help here?

look, I liked this guy right? we go to the same sport and last year i was his bestfriend but we both liked eachother. i confessed, he confessed , then we argued out of nowhere and just never resolved shit. i swear im trying so hard to get over him, but a few days ago i offficially told him i didnt wanna be his friend anymore . AND LISTEN BEFORE YALL SAY IM INSANE, literally he used to leave me on read / delivered for hours on end, if not days. he also had 100000000000 other fuckass " bestfriends" and said the same shit to all of us. and a few weeks before christmas i still saw him as my good friend, until i heard from someone else that he fucking shouted out loud " i prefer my other bsf over mina" that girls name is bryannah idfk that im saying her name, she fucking said she hates me for absolutely no reason at all, told the guy i was toxic, calls my friends pigs, fatties, loners and so on. i KNOW shes the bad influence on him, but to be honest i dont even wanna care anymore cause if he wants to fuck up his own life that badly, go for it. also, every single time i talked to him about how i felt ( venting ) and he always turned it into a whole sad anime backstory for himself. anyways , back to the point. how do i just stop thinking about him and get over him? literally i have tried absolutely EVERYTHING to stop thinking about him. ┗( T﹏T )┛