She wanted him to be good and scared with that letter.

She stayed awake until after midnight, listening for his anxious footsteps; after midnight she stayed awake to cry over the inhuman way he was treating her, and to wish she was dead, and so forth; also because the baby woke and wanted his bottle, and she was teaching him to sleep all night without it, and because the baby had a temper just like his father.
His father's temper would have yielded a point or two, the next day, had it been given the least encouragement.

For instance, he might have gone over to see Marie before he moved the furniture out of the house, had he not discovered an express wagon standing in front of the door when he went home about noon to see if Marie had come back.

Before he had recovered to the point of profane speech, the express man appeared, coming out of the house, bent nearly double under the weight of Marie's trunk.

Behind him in the doorway Bud got a glimpse of Marie's mother.
That settled it.