"my eating habits have not been good over the course of my life"
Ok, you have identified the cause of any problems, and I agree that poor nutrition WILL cause problems. The question is how to deal with it. People like Goldhamer advocate fasting for the problems caused by poor nutrition, see http://www.healthpromoting.com/ and his interesting article Fasting - Back to the Future. But in this case he uses fasting to cure the problems that arise from poor nutrition, for example Neuroadaption, Enzymatic Recalibration and so on.
On the other hand, Fuhrman, who himself healed his leg through fasting and then went on to become a qualified MD does not advocate fasting until you learn to eat properly (which you correctly identified as being the root cause). In fact I know that people who post on this board have asked Fuhrman that very question on his "ask the doc" forum, and he comes out with a firm NO, and he then "prescribes" collards and zucchini.
Whichever side of the fence you come down on...
"I just broke up an orange and was so close to eating it. I had it right up to my mouth, and I was thinking all I have to do is eat this one little piece of orange, and than the fast would be over and I could eat so much food, all of the stuff I've been holding out on over my 5 day fast"
...that sounds as if you have achieved a degree of neuroadaption, so I would say the fast has already done its job. An orange is packed full of nutrition, just what your body needs, and that's why it's asking for it. Although you have not said what else it is you crave. Maybe if you list your cravings people here could tell you if it's good or bad. Good stuff is green vegetables, beans, fresh fruit. Bad stuff is really anything with a barcode on it.
It's up to you if you continue the fast, but my advice is that when you do eat, address the problems that you have identified, namely bad nutrition. Fasting alone will not resolve this, your body needs high levels of nutrients to perform properly, fasting can only help in resetting your taste buds to help you do this after the fast.
Lastly you might want to look at this 5 minute video, which I think explains it well:
(edit) I just noticed in your original post you said:
"Every single second I'm thinking about all different kinds of junk food"
That is a problem, if you mean cream cakes, fizzy drinks and so on. So I guess the question is how to fix that. The problem with fasting is that it leaves your body in a state of needing more nutrients and with a lower metabolic rate, thus eating the wrong stuff after a fast will only excaberate the problem, as many have found.
(edit2)
See also my later post at http://www.curezone.org/forums/fm.asp?i=1364345#i