Summarize:

Accept the grief, sadness, loneliness, regret, anxiety, guilt, insecurity, or other negative emotions in the order they come to you. Let yourself be sad, and let yourself heal. Ultimately, the surest path to getting over someone is to be honest with yourself. Don't bottle up your emotions. Ask your support system for advice, and try to understand what went wrong. If you aren't sure what to do next, these people may have the wisdom and insight to guide you.  Talk to parents, older siblings, aunts, uncles, grandparents – anyone that you feel comfortable asking for insight. You may even feel comfortable asking a favorite teacher or a leader in your community. Be careful who you trust. If you are spilling your guts to someone for whom your crush is a mutual friend, make sure that this person won't pass along what you say. It may be harder to get over the guy if there's gossip floating around. Consider that there are hundreds of thousands—even millions—of people with whom you can fall in love. He may seem like the one, but this doesn't mean that he is the only one. Nor does it mean you'll never find someone like him again. Think about why this crush didn't work out. Maybe you were into him, but he wasn't into you; maybe he was in a relationship already, or he had eyes for someone else; maybe you said something to turn him off, or he did something that made you decide that he was bad news. Whatever the circumstances, you cannot take back what has happened. You can only absorb this, learn from it, and grow.  Think about what you would have done differently. You might be able to successfully navigate a crush situation in the future by analyzing what went wrong with this guy. Think about the sort of person that you want to pursue. Maybe this guy just wasn't right for you, even if you found yourself attracted to him. Consider which qualities will guide your future crushes, and which personality traits you want to avoid.
Embrace your feelings for him, then let them go. Talk about your feelings with a friend, a relative, or a counselor. Remind yourself that this crush is just another fish in the sea. Learn from the experience.