Just give it some time, eventually things will get better. She was your first love so she will always have a special place in your heart! Just keep moving forward :)
i am feeling sorry for you but please be strong
can you talk to her still?
by the way... something in your question is the answer to why she stopped loving you probably. The fact that you wonder if you are good enough... is not attractive to girls. You need to take care of that in yourself to fix the problem. Otherwise you constantly need someone else to make you feel good... and thats not fair for someone else...
you got some issues to work on buddy.. we all do btw. :) I got tons also...
but the fact that you believed someone else's telling you of that can show you something. It means (maybe) that you are not for her in her opinion... But it shows that you don't believe in yourself, if someone else can trash you like that so easily.. relationships can show us our own weaknesses. You can get to the point when you believe in yourself no matter what someone says to you.