Samaiel, why are u so nervous about calling her? Think WELL!
Is it because you still feel something for her when thinking about her?
Or is it fear of the ridicule of the situation, or simply of apologising in general?
If it's the 1st one, then those guys who said not to call her are right. You may start having oneitis and you will feel miserable.
Decide why EXACTLY you want to call her. And don't lie to yourself, as some of us tend to do that!
Calling her because deep down you wanna have another shot at her would be a bad choice, in my opinion. She had 6 years in which the image of you being a bastard had time to get printed very nicely in her memory.
The only acceptable reason to call her would be to do it as a test to see how strong you are, because it takes courage to call and apologise, especially after all this time. Or, like i mentioned before, to erase the guilt and remorse you feel inside. It could indeed make you feel better, assuming she doesnt curse at you and hang up on you when you call her...
Good luck man. Tell us what you decided, and don't feel bad about your choice. The worst thing to do would be to remain undecided. Think about it for a bit, and then make a choice!