Answer:
The climax of The Outsiders includes the part where Johnny kills Bob, and he (Johnny) and Ponyboy hide after fleeing from home. However, a church fire occurs while Johnny and Ponyboy are on their hideout. Although Johnny, Ponyboy, and Dally were able to save children from the burning fire, Johnny gets injured, and this ultimately results in his death after he and Ponyboy return from hiding. Ponyboy meets up with his brothers, makes up his mind to avoid all forms of violence, and starts writing a story of his experiences.
He is referring to the hideous monster inside us all.
What book is this ? if you don't mind telling me