Dude, what you're doing wrong is ignoring my advice. If you're going to ignore my advice, which is what will help you get over her and be happy again, then you deserve all this misery. Block her or learn to enjoy all this sadness. blocking her and leaving her alone is the only solution to your problem. The only. one. stop hoping there is another.
Every day that you ignore this advice, you're gonna spend it alone, miserable, asking yourself all this dumb cr*p and begging for more advice to ignore. If you follow it, things will slowly start to look up. Now, do you want to leave it too late? How much more of your life do you want to waste pining over this one girl?
Now, consider this. Assume you live to a nice old age. Now I doubt you'll die a pathetic old man who still fancies this girl who probably by now either doesn't talk to you, is married, or dead, or whatever. That means at some point you FINALLY saw sense and got over her. Whatever age you were when that happened, you will have looked back at all this time you wasted. The age you're at right now...? This is the age where you have a blast, meet other people your age and perhaps get some experience with the opposite sex, begin your career etc. Right now you're wasting all this. You'll f*ck up your grades, get a sh!tty job and be alone, and for what? Absolutely nothing - this girl is perfectly happy thank you very much, while you're suffering she's getting boned by the guy she does love, working on herself and setting her future up nicely. You're wasting your life dude, you only get one life and all this time you could be getting rich or having fun with the ladies, you're sitting alone, crying and generally having a sh!t time.
Sort this out as soon as possible so you can get the most out of your life. Any rational person reading this would be able to understand the importance of moving on quickly, so if you don't see the need to block her and move on after reading this, you're an utter moron who shouldn't breed anyway. If you're NOT a moron and would actually like to have some fun and perhaps breed one day, then f*cking start getting over her right now, grow a pair and maybe soon you can get a girl who is actually interested in you (as long as you don't become a stalkerish weirdo who won't trust her or leave her alone)
STOP ASKING FOR ADVICE AND IGNORING IT ALL YOU FREAKING IDIOT, NOONE IS GOING TO COME ALONG AND SAY 'yeah this is a great idea she'll want you one day bro!' SO STOP WAITING FOR IT!! EVERY DAY YOU IGNORE ALL THIS ADVICE IS ANOTHER DAY YOU'LL DESERVEDLY SPEND MISERABLE!!!
Is it starting to make sense yet?!?! I don't even know why I'm bothering! F*ck it, if you still won't see sense I'm just gonna leave you to a life of masturbation, with only your own tears for lube.