how do I get him to stop doing this?

I used to have this crush on this dude in seventh grade. He was like my best friend and we would always talk and text. I was manipulated by this girl who was my "best friend" to tell him I liked him - which I did, over a text. Which was completely stupid of me. He rejected me, saying I was a nice girl but he couldn't handle a relationship, etc. I didn't understand what he meant at the time (we were in 8th grade) since I never asked to go out with him. I just told him I liked him.
Everyone used to say that this dude had the biggest crush on me and everyone thought we were dating. I thought he was an okay, nice kid and the closest thing I had to a guy best friend. After I told him I liked him... It was sort of awkward between us. We didn't talk as often and we drifted apart. I stopped liking him in 9th grade since he became a COMPLETE jerk. I'm usually quite the shy person but if you get me mad or anything I can blow out on you so that's what I did.
The thing is... he started telling people I was obsessed with him. "Oh you know (insert my name here), yeah. She's so creepy. She stalks my Instagram and she texts me all the time. She's a freak. She is so obsessed with me, what a creep."
WTF. I don't even follow him on Instagram so I have no clue where the heck he got that from. And he would tell this to girls who could have been potential friends to me (since I didn't really have many friends aside from a few dudes in school... I wasn't a 'loser' or 'unpopular' or anything... I just found it hard to make friends with girls or kids in my grade). And I finally found out why; because that jerk started telling everyone I was creepy. I didn't understand why, since I never did the stuff he said to everyone.
Remember that girl I called my "best friend"? Apparently she liked him around the same time I did and was trying to 'sabotage' my relationship with him. I found texts in my phone to him that I never sent and were sent by that so-called best friend. I'm not friends with