Terry's idea of "rattin' on myself" is the idea that there was a moral conscience pricking at him that he was able to silence effectively.  However, as the film progresses, as people die, and as emotions become more complex in Terry, he can no longer be silent and no longer remain in denial about what is happening.  Father Barry plays a role in this.  This role is most notable when Father Barry speaks to the workers after Kayo's death.  In the "crucifixion speech." Father Barry collapses the  line between those who wish to do nothing and the aggressors in relaying the story of Jesus' death.  In talking about how he, Father Barry, is "going to stand with Kayo" and how others must assume that moral position, Terry begins to realize such truth in his own mind. Something is activated in his own mind and heart and it does not go away. Combined with his growing love for Edie as well as his own misgivings about the direction of his life in relation to being a tool for the mob, Terry threatens and then physically assaults the other workers who are dismissive of the father in his speech.  It was this moment that shows Terry was not really beating up the other worker.  Rather, he is symbolically attacking himself, the person he used to be and the attitudes he used to hold.  When he stands up for Father Barry's right to speak, it is an example of how Terry is "rattin on myself" and how he now realizes who he is and what he must do. [To rat on someone is to tell authorities about another's illegal behavior.]