While sitting outside of the Safeway supermarket in Pacifica, Irene recounts a traumatic story from her childhood to Simon. What is this story is

While sitting outside of the Safeway supermarket in Pacifica, Irene recounts a traumatic story from her childhood to Simon. What is this story is about? (Briefly describe it in roughly 2-3 sentences.) Also, what do you think Irene's childhood story means in relation to her unresolved issues with Simon?

This is Same Difference by Derek Kirk Kim