In Chapter Six, Cole remembers his mother's reaction when he asked her to tell the circle his father beat him... why didn't she speak up?

Cole's mother didn't speak out because she was afraid.

Cole’s mother dusted imaginary specks off her dress, then picked up the feather hesitantly. She opened her mouth to speak, but a quick glance at her husband brought a frightened look to her eyes. She quickly passed the feather on to Garvey without saying anything.