Love gone wrong. iin?

I'm completely, head over heels, in love with someone i met about 4 years ago. I don't fall for people that easily, but I loved him from the moment i saw him, I still remember that moment, and in getting to know him, every single flaw and fancy only proved me right. We got together, briefly, but at the time i was bit younger and awkward, and my feelings got totally in my way, and i acted a bit estranged. Before i knew it time slipped away, and he was totally gone, and we are really awkward if we meet now, and im not sure he even liked me that much. I just have no idea. But couldn't bear to ask. Now years have passed, and even when i've met other nice people, and had brief relationships, all i've ever been able to dream of is him. I met him recently and he told me he had a girlfriend, and i have seen them together. I feel so so so blue, and also such a loser for thinking about him for four years when basically nothing happened. Am i weird? Will i never get over this? No matter how much i try to forget, he haunts my dreams at night, and is my first waking thought. Is there ANYWAY to get over this? Or am i a lost cause?!?And has anyone felt this way?? IIN?

Thanks for reading. xxx