It is super sad for you, it must be! I used to get sad, and I still feel probably a little bit sad sometimes when girls I don't even know that well don't like me... So 5 years? It may take a while to get over this, I understand that you're feeling like this!
Just remember sometimes the problem may not really be you. Sure, if you were more this or more that, as some posters may try to point out to you, she would have more attraction to you, bla bla bla. But it depends on her too, not just from you. Some girls will like you, some won't, and that's because every person is different. Don't you agree? Think about it... Because some girls will like you, and some will not, both of their opinions make sence for them. People will look at you different, which is because of them too, not just because of you.
Just know that you have qualities too and if this girl doesn't like you, fine, there are more women out there who will appreciate you more then this one.
Second, if this one girl doesn't want you in her life then you will have to let her go. You're gonna have to stop looking at her like she is the best thing ever, because if she doesn't like you, can she do much to improve your life? It doesn't matter if she is cute, or has a good personality, if she can't add to your life what value does she have to you? You'll replace her anyway, there are many girls out there with good personalities, which may not be as cute, sure, (or they may) but because they'll LIKE you they can make your life much better! These are the ones you have to focus on, not to be broke up because someone who doesn't like you doesn't want to be with you anymore. Nice, so what? Do you undesrtand what i'm saying?
I just wanna say, if you situation I don't know what to do, but if it all ends it's fine, (maybe you have to let her think about coming back to you if you think she's worth it, you can figure out what to do best maybe) you can be happy single for a while, and relax for a little bit, (Doing some sports, I like to do Tai Chi sometimes, and go to the beach or play chess, browse on youtube, if you have some hobbies great) but just remember there are lots of girls out there, every girl is good on her own way for someone, look for the ones that you think are the most compatible with you and that interrested in you, and if you just want a good looking girl (But is that so important?) then there are lots of those out there too.
BTW I only really read the first post of the thread, so I don't know if this is going to help you out at all, I hope so... But anyway, good look man, I hope you don't suffer much more, that's really really bad... Maybe at least you can learn something from this and become stronger.