The above quote refers to an argument between Christopher's parents. They are arguing about Christopher, and his mother concedes that she just couldn't cope.
And then you and me had that argumant Do you remember? It was about your supper one evening. I’d cooked you something and you wouldn’t eat it. And you hadn’t eaten for days and days and you were looking so thin. And you started to shout and I got cross and I threw the food across the room. Which I know I shouldn’t have done. And you grabbed the chopping board and you threw that and it hit my foot and broke my toes. Then, of course, we had to go to the hospital and I had that plaster put on my foot. And afterward, at home, your father and I had a huge argumant. He blamed me for getting cross with you. And he said I should just give you what you wanted, even if it was just a plate of lettuce or a strawberry milk shake. And I said I was just trying to get you to eat something healthy. And he said you couldn’t help it. And I said well I couldn’t help it either and I just lost my rag. And he said that if he could keep his temper then I should
bloody well keep my temper. And it went on and on like this.