boyfriend cheated and now i feel responsible

18M, 19F. We've been in a relationship for 10 months. Went on a few dates with one of his friends during the time my bf and i took a break in our relationship (he begged me to get back together after 2 weeks, i did). Well, the first date with friend was on our break, and he asked me out again after my boyfriend and i got back together (i didnt know he was still into me). I told him i couldn't and that would be weird because my bf and him are still friends, and he said my bf doesn't have to know, it would be our secret and he would break off contact with my bf if i agreed. <br><br>I knew it was wrong, but i did it anyway. We had sex, and he told me he loved me and wanted to be with me. My bf came back all cuddles, and i felt trapped. I wanted to leave but i love my boyfriend and didn't wanna hurt him, so i told my boyfriend i wanted to break up and started dating his friend openly. We continued to see each other behind my bf's back, and a few more times after we broke up. I should've just broke up with him initially and left if i wanted his friend so badly.<br><br>It's been 2 months since my breakup. I've not spoken to my ex since our breakup in person, calls or texts. My ex has been pining for me on social media and is heartbroken. 4 days ago, i started feeling bad and guilty, and decided to reach out to him and apologise and explain what happened, and hopefully, we could be friends. My ex did not take the news well and has been ignoring me and blocking me on social media. I feel awful now, and i miss him so much. I want him back but i also feel like i don't deserve him and that i've messed it up for good. <br><br>How do i get my ex back, and how can i make it right between us? I still love him very much and i know i've made a mistake.<br><br>Edit: i cheated before we got back together, but continued to talk to the guy after until a week after we broke up. I've known his friend for a few months, and he asked me out the first time we met. I've never felt this way about anybody, and i should've left my ex instead of trying to have both.