Its sad how a daughter can tell if her dad is going to be mean that day or not.
By the way he stands.
Or talks.
Or eats.    
It's sad that she had to memorize the cycle of his good days and his bad so she could know when to make plans to get out of the house again.    
It's sad that she can't tell him she loves him on those days or she'll get yelled at. 
 It's sad
that her dad became the monster she didn't want to know.