The dialogue without context lacks a lot of power, but the concept inside it is accessible even in a vacuum. We can't choose to hate. We can choose not to talk to people. We can choose to say hurtful things to people. But we can't choose to hate them. Hate seems spontaneous. Although there is a distinct reason, people often don't know why they hate somebody - they just do.
This is not exclusive to hate. We don't choose to love, to like, to envy, to pity, or to feel any other emotion. They are all responses to that which is around us.
What makes this extra complicated is that people are so different from one another that the same stimulus (e.g. looking at a dog) may result in completely different emotional responses. And, in fact, humans are so complex that the same stimulus may result in different emotional responses in a single person based on the time of day or any other circumstances.
Remember that all emotions are emotional responses. So find out what they are responding to, how they respond to it, and why that response is the one that came out.