What happened while Mary was reading the book Charlotte's Web while staying home sick from school?

After the tragedy at Purdy's house, Mary felt much more content staying with Hector's sister, Alecia, because she was much older and certainly more sane. Mary was mistaken, however, and was shocked when she saw Alecia smack her husband over the head with a frying pan, knocking him out cold. After this event, Mary begged her mother not to leave her overnight anymore, regardless of who she stayed with.