Ex won’t leave me alone

So I’m 18 my ex is 20, we’ve been dating for two years. But a month ago he anonymously texted a girl that he loved her. She didn’t know it was him but I knew it was him. And anyways I broke up that day on the a lot when I saw it. And every day since that day he’s been contacting me. Writing me letters, calling me, and messaging me of how sorry he is. So I blocked him on messenger. And now he got a new number because I took him off our phone plan and now he’s texting me and calling me saying he’s sorry. What do I do? Like obviously I still love him but what he did hurt my heart. Help me!!