Okonkwo hung himself because he knew his clansmen were not going to fight with him.
Okonkwo hanged himself because he felt powerless after his society had been fundamentally changed by the arrival of the white colonizers. He realized that the traditional ways of his people were no match for the influence of the colonizers and he could not see a way to rise above it. His suicide was a final act of defiance and a way to maintain a sense of control over his own destiny.
Okonkwo justified his part in Ikemefuna's death by believing he had to show strength and not appear weak. He convinced himself that he was acting in the best interest of his family and his community by following the customs and expectations of the tribe.
Okonkwo was buried in the Evil Forest, as punishment for committing suicide, which was considered a grave sin among the Igbo people in Chinua Achebe's novel "Things Fall Apart".
When Okonkwo thought of his father's weakness and failure, he would work and become successful to prove to himself that he is nothing like his father. He would think of his own shows of manliness to silence the thought that he might be like his father.
Okonkwo hangs himself because he is unable to adapt to the new society. He knows he will be imprisoned, (and probably executed) for killing the messenger. He is also a proud man, so prefers to take action into his own hands. By killing himself, he controls his own destiny instead of letting the Europeans control him. He also knows that his clan will not fight the Europeans. Some have argued that he hangs himself because he is ashamed of his village, but if that were so, than he probably would not have killed himself, which is a sacrilege to his village.
When Okonkwo thought of his father's weakness and failure, he would work and become successful to prove to himself that he is nothing like his father. He would think of his own shows of manliness to silence the thought that he might be like his father.
Only Obierika's reaction is shown in Things Fall Apart. Obierika is driven to despiar and anger at the District Commissioner and his men. He considers Okonkwo one of the greatest men in Umuofia. Later, in Arrow of God, it is revealed that Okonkwo was lionized as the symbol of the pride of Umuofia and the Igbo as a whole. Okonkwo rejects living in a world where he would have to sacrifice his pride and demean himself before a greater colonial power.
In Chinua Achebe's novel "Things Fall Apart," Okonkwo commits suicide by hanging himself after realizing that his clan will not resist colonization by the British. He chooses to end his life rather than live under the control of the colonizers, maintaining his sense of pride and dignity in his own way.
Okonkwo becomes a father to Ikemefuna, and Ikemefuna calls Okonkwo father. Ikemefuna is like the second man in the house, the closest to Okonkwo's personality, and helps to develop Nwoye's manhood. Okonkwo likes Ikemefuna, but does not show his feelings towards Ikemefuna because to do so would be unmanly.
Okonkwo likely shivered because the last time Ezeudu visited him, he predicted that Okonkwo would have a severe loss, which was later confirmed when Okonkwo's gun exploded, accidentally killing Ezeudu's son. This memory would have triggered fear and anxiety in Okonkwo, as it reminded him of his impending misfortune.
The District Commissioner treats Okonkwo's suicide with amusement and finds it an interesting curiosity which would be worth a paragraph in the book he is writing. He is relieved that he does not have to deal with arresting and hanging Okonkwo, as Okonkwo has already done it for him.
Okonkwo does not ask Ezinma to not marry, but rather to not marry anyone in his motherland of Mbanta, as then she would become part of that village. Okonkwo would rather have her marry a titled man in Umuofia, to increase their family's influence and togetherness in Umuofia.
Okonkwo believes that Ezinma possesses traits associated with male strength and courage, such as perseverance and intelligence. He sees these qualities as more valuable and suited for success in the Ibo society he lives in, and therefore wishes Ezinma had been born a boy.