Mary felt like her world had begun to crumble right now. She didn't want to believe all this because her son told her a different story.
Kate was supposed to be this useless and barren woman that got lucky because she married a perfect man like her son. She should be grateful that Matt hadn't divorced her yet, because he definitely deserved someone better.
"Y—You liar! How could you slander your own husband like that?! Don't you see that he is too good for you? You ungrateful wench!"
At this point, Mary was also unsure of herself.
She wanted to keep thinking that Matt was the family's breadwinner and that Kate was just a leech.
But the confidence in Kate's voice actually began to shake Mary's belief about her son.