need advice about how to deal with this guy who’s still hung up

hi guys, this is a bit of a long story and I need unbiased advice so if you have some time I’d appreciate it, really.

Basically it started back when some guy in my school grade dmed me. I thought it was purely platonic or atleast maybe I wanted it to be which is why I envisioned it that way. We talked for a month or so, he got me a birthday present (which I didn’t ask for and was kinda unsure about then after a bit he asked me out. Over text, saying he enjoyed the time we’d spent together and the memories we’d made. Now this might sound all cute and all but in reality, we’d talked in person maybe three times, I was treating him as a friend (and I’m not attracted to him or like him more than a friend). Idk what memories or moments he was referencing because most of our conversations he instigated and he talked about random stuff, nothing deep. What uni courses, our likes and dislikes nothing deep enough. Maybe I’m juts more traditional but that certainly was not enough “get to know stage” for me to date someone and I really did not see him beyond a platonic relationship. So I rejected him in the nicest way possible. The it’s me, I’m not ready, ur a nice guy and all but I don’t see you as more than a friend. I hope this doesn’t mean we can’t be friends yada yada I was tryna be nice, polite but to the point. I even thanked him for being brave enough to ask me out cuz I know it’s not easy and apologised if he felt like I led him on in any way. But for some reason he wasn’t really taking it and maybe this was cuz I was being too nice idk. He was like “I’ll wait for when ur ready and “does this mean I’ll have a chance in the future” and I was tryna be nice but I was also like no, I don’t see you as more than a friend. And it got to the point where I was repeating myself. Like I was really not interested in him that way and it started giving me icky red flag energy. Anyways we break it off, stop talking delete the chat (per his instigation) and he tells me not to tell anyone. So as a girl I only tell my best closest friend and no one else. Out of respect. Not a day later he dms my best friend saying “do you know yet” and she plays dumb and says no as she should. He then the next day he dms me again saying “you can tell her” so I’m like okay so she doesn’t have to play dumb anymore. Then here’s where things get super weird. He dms her for days after complaining, saying how sad he is and how heartbroken he is after I said no. (Side note: when he dms her he hates sayin “rejection” he literally said to MY best friend “no don’t call it a rejection call it opposite of yes”. Like what). he yaps to her for days about how sad he is and of course my best friend tells me everything. And I’m so weirded out. He is not by any means close with MY best friend and suddenly he’s dming her every day about me like he doesn’t have friends he can tell. I’m also like 99% sure he allowed me to tell my best friend about his rejection JUST so he could whine to her about it. I still had some sympathy at this stage because I felt very guilty about rejecting him. A month goes by and he’s stopped messaging her after the couple weeks after the rejection. Then school starts again and he texts her again whining to MY BEST FRIEND and being sad about it and she’s feeding me back all this information. I think it’s weird that he’s even talking to my bestie like I’m super weirded out. Then two weeks go by and he unfollows me on Instagram. Now I don’t notice this until I get a notification saying he requested to follow me. And I was like huh? Doesn’t he already follow me so I checked his profile. He removed me as a follower and unfollowed me. Now suddenly he requested me back so I was like you know what. No, I’m not gonna accept it, atleast not right away so I let it sit for a couple days. Now after the days roll by I forget about the request UNTIL my bestie pulls me aside and shows me a new dm conversation this dude pulled her into. Now this is where I lost all respect, empathy and gained a sense of rage. He called me crazy. He acted like a victim telling MY best friend, “she unfollowed me haha it’s kinda funny”, “I don’t know what she’s thinking doing that like what does she want to gain from it” “it’s super dumb that she did that” and I QUOTE “she’s crazy”. NOW THIS IS ALL TO MY BEST FRIEND MIND YOU SO I HAVE NO IDEA WHAT THIS BOYS THINKING. He tried to paint me as a villain since I supposedly unadded him and removed him as a follower (WHICH I DID NOT) he was the one who unfollowed ME and removed ME). like he’s trying to gaslight her into thinking I did something bad by supposedly unfollowing him when he was the one who removed me. Luckily I already told her everything about the requesting again before hand so she knew he was lying. But HE CALLED ME CRAZY. I lost it I was so mad I had to take a breather after reading that. He also is continue to talk to my best friend as if they’re besties when they’re not even close. It’s also super dumb because there was another situation when we were still on good terms and talking where I bought him an iced coffee. Now this wasn’t because I wanted too but because I happened to be at a cafe with my friend. He texted the friend asking where she went and she said the cafe and asked if he wanted anything. Now he knew I was with said friend but didn’t text me and texted her and was like “I want an iced coffee from a supermarket I’m tired”. She had ordered a coffee fresh and was waiting for it and I was too with her. It was getting close to class time so I offered to buy the iced coffee at the different store so we could get back on time and she said I should so I did. We’re in class when we get back so I give him the coffee in person when he’s with his friends. I didn’t buy him the coffee for him. It’s because he asked my friend for one and it was a convenience thing. Now the other guys he was with saw and are encouraging him to ask me to formal at the end of the year (this is after I rejected him) and hes not willing to tell his friends he got rejected so now it seems like we’re still talking and possibly flirting when we’re not. I’m scared this stops my chances of other people asking me to formal too since they think he might (even tho I hate him now). Anyways this whole situation is really weird. I want to tell everyone in my grade that I rejected him juts so people stop making assumptions and to stop him from being weird and talking to my best friend about me. I’m not sure if this made any sense but if you read all of this and have any advice is would seriously appreciate it because I have no idea how to proceed I’m juts too angry he called me crazy.