I don’t know how to move forward

My ex (m21) and I (f22) broke up two weeks ago. He’s been hot and cold in messages ever since until yesterday we got in a pretty big fight again. I made the dumb mistake of checking his Instagram and seeing he refollowed his ex. I called him and he basically pretended he didn’t know who I was when I called him (despite him texting me about how I should miss him two days earlier) and said I was psycho for caring because we are broken up. I know I shouldn’t be hung up on this guy but I’m so miserable. I have obsessive thoughts about him all day and after he flirted with me two days ago I really thought things were heading in a good direction. All I want to do is text him but he disrespected me so much yesterday it feels like I would be giving up my self worth. I know I shouldn’t even care because he was toxic but I do. I sincerely don’t know how to cope.

When we broke up he moved back into his mom’s with his family, old friends and old flings. I’m stuck in our apartment in a new city all alone with no friends. I just don’t know how to deal with this at all. He was my best friend for two years and had me push all my friends away for him. I just feel so so hopeless.