Proctor's conflicts are explicitly discussed in the play. His moments of torturous private doubts are shared, rather privately, with Elizabeth and his more external conflict with Abigail is discussed early in the play with Abigail then later with Elizabeth.
For the most part, Elizabeth functions as the sounding-board for Proctor's private conflicts. He debates his penitence with Elizabeth in Act II, talking about the affair he had with Abigail and his difficulty in finding any forgiveness from his wife. He also talks with Elizabeth about taking action to stop the fraudulent trials.
Finally, Proctor discusses his moral crisis as he faces the gallows. He feels that he is not good enough to sacrifice himself for honor and choose death. This is why he considers signing the false confession. This crisis is also at the heart of his character and at the heart of the play (Can one person maintain integrity even when caught up in a mass dissolution of personal responsibility and a public abdication of moral law?).
At every turn for Proctor, Arthur Miller provides a confidant so that Proctor's internal and external conflicts can be verbally expressed.