going through a break up...

My ex keeps posting this girl on snapchat and it is SERIOUSLY PISSING ME OFF. Like two days after we broke up he started posting her & ignoring my texts and snaps. Lol he even ended our streak. When we were together he used to tell me he’s not close like that with any girls and he used to get annoyed at me when I spoke to my friend who is a boy. Now all of a sudden he’s posting this chick. And I just feel so stupid because I was trying so hard to make our relationship work. We broke up because he never made time for me wen we live 15 minutes away from each other. He just kept giving excuses and empty promises. I kept sending these long messages saying i miss him and stuff like that. Ever since we started college he’s just been acting DIFFERENT. The last time i saw him was 2 days befroe we started college and now it’s nearly been two months since I’ve seen him. Cos we go to different colleges now. Anyway wat im trying to say is it’s making me sad seeing him getting close with another girl like this. I really wanna see him. I really wanna talk to him. It was literally so random the way how he cut me off. I used to cry every time i thought about him. Im 17, please dont tell me im too young to be worrying about boys or anything like that. I seriously loved him and still do. We were together for basically 4 years and now he’s just stopped talking to me and started talking to HER. Yeah im not gonna lie i am jealous. I miss him. I love him. I even told him i still love him and i miss him a couple days ago but he just ignored me. So i stopped trying to contact him but its so hard. We used to talk every day and we were so close and now he dont talk to me. I havent cried about him in so long but just writing this is bring tears to my eyes. I don’t know. I just feel betrayed. Imagine a couple days before he completely stopped talking to me he told me he loves me. But he’s putting me through all this and making my chest hurt and making me cry all the time. He knows i am an emotional person he knows what im like. It hurts i just dont know what to do. I have no one to vent to. Every time i try to talk about it with someone they just change the subject. Or tell me to forget about him. BUT ITS NOT THAT EASY. I still think about him all the time. I wonder if he still has the gifts I bought him or my clothes or pictures of us together.. i still do.. anyway let me just wrap this up now I really miss him and i dont know what to do help please