Going through a rough time

So me and my boyfriend of 4 and a half months were perfect. I was so happy. Everyday I would wake up with a smile on my face. And then one day he started acting weird. He didn't text me for 2 days, and then when he did, he sent me a long paragraph saying how he didn't want a relationship or anything anymore because he's becoming a senior and he just wants to focus. And then a day later I see this girl post a picture of him captioning it "my boy😍". As if I wasn't already hurt enough, I think I'm depressed now. I love him so much. And now they are dating. Everyone is telling me how they won't last long. But it hurts so bad. It hurts because he told me how much he loved me and how he would always be by my side and could never imagine hurting me. I even lost my virginity to him. God this pain hurts so much and I've been crying for a week straight. I can barely eat anymore, I've lost 6 pounds. I hate this pain so much.