
rom the screenplay: 
Alma:  "Don't try to fool me no more, Ennis.  I know what it means.  Jack Twist?"
Ennis:  "Alma...."
Alma:  "Jack Nasty.  You didn't go up there to fish.  You and him...."
Ennis grabs her wrist and
 twists it.
Ennis:  "Now you listen to me, you don't know nothin' about it."
Tears spring to her eyes, she drops a dish.