A few days ago, an interview with longtime Papal Secretary Msgr. Alfred Xuereb appeared. The interview is a candid and emotional account of the events surrounding the resignation of Pope Emeritus Benedict. Msgr. Xuereb became the Secretary of Pope Francis following his election, and just now has been promoted to the #2 position at the new Secretariat for the Economy, an appointment that shows the total trust of yet another, and very different, Holy Father.
One of the many helpful points in the interview is the discussion of the Holy Father's prayer life prior to his resignation, and the times he began Mass later than usual, because he was absorbed in prayer. Likewise, the tapes of the resignation show the emphatic, emotional way the Pope spoke of examining his conscience, "iterum atque iterum coram Deo," "again and again before God" (starting at the :15 mark in the video below).
The worst of the Dan Brown conspiracy theories have thankfully quieted down since the anniversary of the resignation has passed, but for those who have lingering doubts, perhaps they will believe this eyewitness testimony. The interview appears in two parts, here and here.