What was Braverman's struggle and how did he overcome it?

In the story, Braverman struggles with his anger after Millstone hires three men to beat him up. 
We get an idea of how upset he is in chapter 13. In that chapter, Hope is in Braverman's home; she is visiting him in the aftermath of the attack. During their conversation, Braverman admits that, if he had been able to break free, he might have killed any one of the men who held him down. 
Braverman tells Hope that his anger frightens him, and he has begun taking out his anger on his mother and little sisters. He is not proud of the fact that he yells at them, but he feels helpless. It's clear that he is struggling to process his anger in a way that is constructive.
Since Braverman isn't one to let difficulties cripple his motivation, he decides to channel his energy towards getting G.T. Stoop elected. He takes the first step of writing an article for the Mulhoney Messenger, detailing his attack and reaffirming his support for G.T. Stoop. Through his article, Braverman lets Millstone know that he won't be intimidated by the latter's corrupt tactics. 
Braverman also takes the courageous step of confronting Millstone after his speech at a Methodist church picnic. Braverman is joined by fifty-seven teenagers, who turn up to show their support for him.
In all, Braverman overcomes his struggle with anger by channeling his energy towards getting G.T. Stoop elected, rather than submitting to self-pity or other types of destructive behavior.