My friend had sex with my boyfriend, and it was my fault

EDIT: Wow, this blew up. Thank you all for the comments and advice, I am working on myself. I have a feeling a couple of you are my classmates who also know my ex, but I will use your advice regardless of who you are. Thank you all again.<br><br>I (18F) met my ex (17M) at summer camp before senior year. We bonded over a bunch of things and were sexually attracted to each other. We had sex for the first time at camp, and I was happy. I had thought I was in love despite knowing him only for a week or two. He went down on me first (I was on my front), then I gave him a blow job, then I rode him for a while. After a while he turned me over and we had sex for a bit. Finally we got me on my front again and had doggy style for a while. I played with myself during that. Condoms and lube were used in all scenes, because I am a graduate of lust.<br><br>We returned home and remained in contact through texts and snapchat. Since we went to different schools, we only saw each other twice. One time was a sporting event and the other was when he and some of his friends went to a party at my house. We hooked up at the sporting event but not the party.<br><br>Fast forward to the beginning of this semester. I realized that I had never contacted him outside of replying. I knew I was hooked on the idea of dating him. We were planning to see him at the state championships, and I realized that I couldn’t get together with him when we were together again. So I “broke up” with him, but really it was me realizing that I was just infatuated and needed to move on.<br><br>I remained in contact with him because he was my only point of contact to some other people from camp. He didn’t respond much anymore, and when he did he was short. But I didn’t care because I was moving on.<br><br>Then my friend (18F) told me that she saw him at a party and hooked up. I wasn’t mad at her, but now I had no way to contact these people because we weren’t friends. I had assumed that I would be able to talk to them despite my ex and I not seeing each other again.<br><br>Fast forward a few more weeks. My friend hooked up with him again, and he told her they were dating. She was excited and told me when she got home. I was mad. I realized that I never got over my infatuation, and that I still had feelings for him.<br><br>I am mad at myself for even letting this happen. I feel so stupid. I hope I can move on, but I am going to miss the idea of dating him.