Codependency crises - please help

I'm sorry, I don't really know how to work this website, but I'm going through a situation I've had anxiety about happening for years.

The day has come that, someone I've made myself dependent on for my happiness - our relationship's finally crumbling.

We spoke daily for years and years. He understood every fibre of my being, and cared enough to try and improve it. He addressed every issue of my past, made me realize that the abuse I went through as a child, and made me feel for the first time in my life that I wasn't lying about it. He helped me learn about self-respect. Our friendship, our love was about more than that though. We shared hobbies that my life revolves around, and he became such an integral part of my world. The center of it. Nobody could make me feel like he could. 

It might have been a purely online relationship, but that just made it all the more special. Our little chatroom was our paradise away from everyone else, our escape from the real world. There, he was all mine and I was his. There was never a romantic side to our relationship, but we still love each other deeply. However, I've been... For at least six years, quietly terrified of the day it would crumble and he'd move on. 

Without any real warning or reason, that's happening. We still care for each other, but I think the weight of our relationship has turned things sour for him - I was stronger earlier today, and I advised that we take a break from each other. I said that I'd learn to be independent, that I'd center my world around myself rather than him. He said that he could make no promise that he'd be back in my life, and he should treat this as if he's leaving forever. 

I'm riddled with social anxiety. I'm desperate to support myself with a job while I study, to learn to drive for more independence and freedom (especially given I'm 23), but I'm... so scared of getting a job because I feel like I'm a failure, that I can't do anything right and I'm terrified of people seeing and talking about how useless I am.

When I was involved in domestic disputes, he was there for me;

When I was studying, he was there for me with praise and support;

When-ever I showed the smallest inkling of feeling insecure, he was there for me with love and consistancy;

Whenever I was down, he was there for me with dry and cheeky humor he knew would make me laugh;

And now, in a course of... days, six+ years of that has crumbled. 

He advised I read into psychological research about 'codependency'. And I am. I'm so, so codependent on him for my happiness and validation that I don't know how to live for myself. 

God, please help me. My worst nightmare is coming to life and it hurts so bad.