Good point. But the word "need" is also used in the sense of "strong craving". And strong cravings can be selfish both in regard to what is craved and in regard to how the craving originated. For example, someone starts going to expensive designer shops and comes to need the attention and flattery of the sales people there. Similarly, gamblers may need the next thrill, drug addicts the next fix, and so on. In such cases the word "need" does not imply a desire that is natural and important.

Because you take a position to be something one can act on, I interpret this in the sense of "commitment" or "disposition". So suppose a person has the deliberate disposition to "fix" student grades whenever he is offered $100 or more to do so. (This might be a professor or an administrator or a person with access to the university's computer system.) Surely this is an unethical disposition, that is, a disposition that one ought not to have, and the person so disposed is typically unethical on account of this disposition even if he never engages in any unethical conduct (e.g., because he is never offered a sufficiently large amount). It's different with emotions because these cannot be simply willed away. It is problematic, then, to characterize a person as unethical on account of an emotion that she just finds herself having, without choice. Still, we do have ways of influencing our future emotions, and there are surely emotions that we ought to try to diminish or eradicate (e.g. disgust for...

Nietzsche and Camus come to mind. They don't exactly address emotional apathy as a philosophical problem. But they both develop philosophical positions that, in quite different ways, combine intellectual argument with emotional engagement. You might have a look at Nietzsche's Thus Spoke Zarathustra and Camus' The Rebel .

That something much worse exists does not make a bad thing less bad. But it may well make you feel much less bad about it. And that's what a consolation is, really: something that makes you feel less bad. In this case, this can be achieved by gaining a broader perspective: by seeing the wrong you suffered in comparison to other wrongs (and, I might add, also in comparison to all the good times you have had, and will have again, with your sister). However big and irreparable the hurt felt at the time, it's really just a blip on a larger canvas.

A very nice classic essay on this question is "The Conscience of Huck Finn" by Jonathan Bennett. I think you'll find it congenial and responsive to your second and third questions especially. I found a version on the internet: http://www.earlymoderntexts.com/jfb/huckfinn.pdf