Focus on yourself, what makes you happy, work, friends, gym. Its not going to be an easy road to recovery but at least you've realized that your love and affections are not being returned.
Sometimes at "the moment" the guy may seem like the one, you cant stop thinking about him how everything is perfect, except for that one missing token. He doesn't feel the same back, sometimes love takes time to grow, other times its just not meant to be. It may take a bit to see his true colours and there might be cues all along to something. You'll look back and think "damn, what the hell was I thinking?" I've been there before and it took me a number of years to really get over it. You, it might take a few months, or weeks. The first few weeks are the hardest, its constant the pain, the thoughts of him. Some folks find the need to talk things out with that guy. While everyone does things differently, i dont suggest it. Sometimes its like peeling open a scabbed over wound.
Everyone copes differently, some go and meet others, talk with friends or hook-up alot, I keep to myself and goto the gym alot. Work helps sometimes in keeping your mind occupied for a little bit, if it doesnt initially, it will over time. The depressed/hopeless feeling is natural, thats what makes us human.
Try your hardest to focus on you, hang out with friends, I found that talking things out with my closest friend as redundant as it often gets, helped ease the pain the most. If he/she is your best friend they wont mind listening, thats what they're here for, to pick each other up in a moment of weakness.