The first thing that Proctor does is cut off his relationship with Abby; we see his determination to end it and keep it that way in the very first act. When Proctor comes into the house to assess the Betty situation, in a moment alone, Abby sidles up to him and starts talking to him. She really wants him back, but he firmly states, "I will cut off my hand before I'll ever reach for you again." You can't get much clearer than that. He stands his ground, even when she is flirting with him, and even when she gets angry and hisses insults at his wife.
The second thing that Proctor does to move away from his sins and find his own goodness is that he does all that he can to save his wife and other people's wives from the clutches of the witch hunt. He goes into town with a petition, with Corey's statement, and with his own encouragement of Mary Warren. He leads all of these charges against the court and against the accusers. This is a brave thing to do, especially considering how much power the courts have, and the girls' power to accuse anyone who displeases them. Doing such a courageous thing helps him gain confidence in his goodness.
Another very brave and good thing that John does is confess his sin, in public, to the entire court and town. And, he does so that he might save his wife from being hanged. In front of the entire courtroom, he confesses about Abby, "I have known her, sir," an admission of his affair with her. To defile his name, renounce his membership of the church, and connect himself to a lying, conniving girl (Abby), all to save his wife, is an act of extreme integrity and bravery.
Last of all, and most importantly, John Proctor does not confess to witchcraft--to a lie--and hangs on the gallows. This final testament of honesty and courage finalizes his repentance, and allows everyone to know that he will do anything--including die--to do what is right. As he makes that final decision, he finally reaizes that "I see some shred of goodness in John Proctor." With that peace in his heart, he goes to the gallows.
I hope that those thoughts helped; good luck!
John Proctor moves past his sin, from having an affair with Abigail by moving on. John Proctor tries to please his wife in everyway possible, some examples in ways he does are, considering buying a heifer(pig), by adding salt to her soup, to make it better to his taste, then telling her he loves the seasoning of her soup. John eventually breaks down (in a type of anger) and tells his wife her justice could freeze beer. John also tries his hardest to defend Elizabeth from having to go to jail, after Abigail accused her of witch craft. Hope this helps, this is my first answer :/