Missing my ex like crazy

Okay so basically me and my boyfriend broke up exactly a month ago and this has been the hardest thing I've ever been through. He's that kind of guy that everyone knows for being a guy who messes around with girls ya know? But during the summer we started talking more and he started flirting and we hung out a couple times. The problem was that he dated 2 of my really close friends and I didn't know if I could do that to them. So he asked me out a couple times and I didn't say yes or no I just said idk. I thought about it a lot. Because he was trying so hard for me for a really long time. And I finally decided after not dating for almost a year to say yes and at least give him a chance. So I said yes and we started dating July 17. Everything was going pretty good he treated me right, didn't talk to other girls, I was very comfortable around him which is hard for me, and I felt good about this relationship. Then I would get random feelings were I didn't like him anymore and then I would get super strong feelings that I couldn't control about him. But then I knew as soon as school started that's when everything would go downhill. I kept having people come up to me and tell me that he was messin around with other girls at school and im the kind of person to forgive stuff like that and I did. So then I realized he stopped sending me cute messages, stopped putting in as much effort, and it started getting to me and I didn't know how to tell him so I didn't. A couple days before we broke up he went to a party. There was obviously gonna be girls there and so I basically told him if he doesn't text me back I'm just gonna assume that he's messing around with other girls. He didn't text me back for 2 hours. I went on snapchat and started watching people's stories and I saw him hanging around with a certain girl. And it's Sean so obviously he's gonna do stuff so I kept watching and they were messing around with eachother in everyone's stories and he was posting stuff in other girls stories. And so I texted him and I said "just don't talk to me" and he said "that mean you tryna break up?" And I kinda went into shock and said no I just wish you wouldn't do stuff like that. And we kinda talked it over and went back to normal but then on Monday he came up to me and asked me why I was mad and I didn't say anything because it's pretty obvious why I'm mad. But anyways long story short he tried to set me up to see if I was loyal and I said one wrong thing and I wasn't even bad and it didn't mean what he thought it meant and his friend screenshotted it and sent it to him. He stopped texting me and I instantly noticed and asked what was wrong and he left me on read. So I texted him again and asked him what was wrong and he replied with "nothin man" I'm sorry who's man? But anyways I tried to explain the text and he still didn't believe me so he broke up with me by saying "I don't think this taken shits working for me, we gotta break up Brody 💯" Once again I'm in shock and I just said "okay but I find it funny that as soon as I do one thing "wrong" your ready to break up even after I gave you so many chances" and he left me on read. So what I'm trying to get to is that I didn't have closure. We never talked about what's gonna happen after our breakup and we never decided to be friends. And I have to see him at school everyday and every event I go to he's there and it kills me inside to think that I would of been with him all the times I saw him out of school but we broke up so.. but yeah like I said I don't have closure, I want to text him but I'm scared he's gonna reject me or he's not gonna wanna be friends. I just want to be friends again like seriously we were such good friends and then we dated and ruined everything and I just don't know how to approach him and tell him how I feel. I miss him like crazy and I just want to talk to him. I just want to know that he doesn't hate me. Everyone tells me I didn't do anything wrong but I still feel terrible for what I did and it's my fault we broke up. I know nobody is gonna read this but I just need closure or a solution. I need to talk to him that's all want.