decency, a lack of justice?

As per our in-class discussion, decency as I am told to understand it is a step above justice. It encompasses the knowledge of true equal justice and chooses to ignore it, so to speak, for some greater good, presumably some person(s) benefit(s). I get it, and I see how it appears this way, but I still have trouble wrapping my head around the idea that decency is above justice, and therefore something more than but still part of justice in the equal sense, while it does not permit any sort of injustice. Simply put, does it not seem that if one chooses to ignore the equal justice for the sake of another, then one is doing himself an injustice? For example, take 1, 2, and 3. 1 is the excess of justice (some benefit in this case), 3 is the lack of justice (some amount of injustice), and 2 is the mean (equal justice for both parties). If person A and person B receive equal justice, they are both 2. But if person A decides to be decent and regard himself as a 3 so that B may receive 3, is not A receiving some sort of injustice, even if self-inflicted?

1137b "For the decent thing, though it is better than a certain kind of just thing, is just, and is not better than what is just by being of some other kind. Therefore the same thing is just and decent, and while both are things of serious worth, what is decent is superior."

This quote summarizes Aristotle's view of decency, as well as what I stated at the beginning of my argument. If we read on though, Aristotle admits the impasse.

1137b "...what is decent is just, [but] it is not so according to the law, but is a setting straight of what is legally just. The reason is that every law is universal, and there are some things about which it is not possible to speak rightly when speaking universally."

Aristotle continues to argue that one must approach every determination of justice on a case by case basis, with which I agree. And I agree that the universal laws of justice, those set about for laws, are imperfect in that one cannot apply them in the same way to every case. In this way, decency is required and seemingly some sort of lens through which one must look upon the universal laws. Regardless, I still believe that person A is being done some injustice, however small. Maybe money is a bad example, but I think about when I was driving and was rear-ended by an elderly woman (she could barely see over the steering wheel). I got out, and there was little to no damage. Considering her condition and the detriment (to her) that reporting this accident might have caused her, I shrugged it off, told her it was fine, and went on my way. I believe in this situation I did the decent thing. However, my car's rear bumper was scratched and slightly dinged and I felt as though I had been dealt some injustice, even though I think I did the right thing. (Although, the thought of who she might hit next and how far worse her next accident could be has not since then escaped my mind).

Am I making sense?