There is nothing wrong to break a NAP, it is human nature and human nature is dark by nature.
Besides, unless specified in game setup, there are no punishment for breaking a NAP.
Now if you break a NAP, others will note it and play with you (or not) accordingly. This information is also useful for anyone who may considering playing with you (or not).
So this "I broke NAP for a thousand reasons and I believe I am right so you do not tell others about me or you are angry and sissy" attitude from "NAP is for losers to stick to" camp is quite disturbing to me. I see whole lot of justifying in breaking NAP, but for what? You do what you want to do, but a thousand excuses still do not make you as trustworthy (in the game anyway).
Without trust, there is no point in NAP whatsoever. You showed your excuses, you even convinced yourself, now let's move on. No you cannot change other's perception of you by finding even convincing excuses.