Someone keeps texting you, but you hate him and don't want to break his heart. What should I do?

If there is a person who I hate but often sends me text messages, the way I won't make him sad is to fight back at his disgust and reply to every text message. If I don't want to make myself unhappy or upset him, then I'll turn off my phone or change my number, and then I'll set to reject the message he sent. If not, I'll pretend I didn't receive it and don't reply.