Breakup help 😭

So i was dating this guy and let’s call him D. D and I were dating for a while and I liked him a lot. One weekend I had to go somewhere with my family and he was sad that i couldn’t go to a festival with him. Apparently he had to third wheel his best friend, and his girlfriend brought a “friend of hers” so Devun wouldn’t be weird? Idk I don’t really understand. Well I didn’t know this until my best friend texted me and told me that D was at the festival with another girl. Of course I freaked out cause I didn’t know that he was going with another girl, all he told me was that he was third wheeling. well an hour later he called me and said we were down because I “hurt his feelings” and the girl he left me for (let’s call her E) took the phone from him and started cussing me out. Oh also that exact day I spent over $130 on him for his birthday. The next morning he texts me and asks if we can still be friends and the reason why he broke up with me was because “I made him bleed by scratching his arm” and “I get grounded to much” and he “thought I was cheating on him” which none of those things are true, in fact he left me with a scar. He kept changing the story. Anyway the next day was school and he made it super awkward. I have 5 classes with him and in all those classes I sit right next to him. He told all of his friends that I cheated on him and every time I saw him he would yell “E! E! E!” He still does it to this day and it’s been about 4 weeks how do I get over him ? (Also here’s the scar he left me)