"Die and I will take my own death at whatever time Zeus and the rest of the immortals choose to accomplish it." (XXII, 268-269)
Achilleus claims that he is satisfied with dying whenever the gods descide it is his time, because he has finally killed Hektor. In my opinion, Achilleus' wrath is only semi-justified. He had the right to be angry at Hektor, for killing Patroklos, but I do not think Achilleus had to go as far as killing him. Achilleus knows how important someones pride is, and that is why he had to disgrace Hektor by dragging his corpse through the dirt, after killing him. That can not even be discribed as revenge, that is cruel and hateful. Achilleus' actions are often rash and he is often headstrong, as shown in this quote.
Achilleus' wrath towards Agamemnon was on a different level than his hate for Hektor was. This anger, was more for his eggo, and glorification, rather than revenge. The two warriors were in essence fighting over women, Cryses, and Brises. This anger can not be justified, because it delt with their self-satisfaction; they were not fighting for something significant.