OP, I know how you feel hey. I had girls I found attractive before, they were easily got over with. But yeah, I really liked this girl once since she was first girl to talk to me and she's like attractive and all. I eventually sent her a card telling her my feelings for her. She nicely wrote a letter back saying that she's not my type and that there is just no chance for anything to happen. That had upset me a lot. I went on to feel for her at a distance for like most of my high school years. In that time I probably went trying to find another girl as a substitute for this one. One I missed out even though she later said that maybe I had a chance with her (Doh!!) But the next one started my depression even now. Since then I tried going for other girls, went out with one for a bit, got together with another as official couple but that only lasted for ~2 months. And like you, I threw my life away, shut myself in my room after uni, going to this low paying job, so I guess what I'm saying is that you are not alone in this OP. Doesn't help with your problems but I know from experience people such as you and me dont wanna feel that only we are stupid enough to be like this. But what is different from you though, I don't know, you might be better now, but I try to talk to more people, guys girls it doesnt matter (coz hey, a guy friend might be able to intro u to a girl who might accept you, never know), went out to things if I could, and all that.
When life sucks, all you can do is crawl through it one hour/day/week at a time and hope for the best while doing something so that when the time comes you are prepared.