Cersei is used to getting her own way. Whether its by her own powers of manipulation, or her looks, or her family name and the threat of Tywin or Jaime. Shes used to people doing as she tells them, and responding in the appropriate manner when threatened by her. Now, stripped of her finery, faced with enemies that she cannot hope to threaten or manipulate, and with only Qyburn for a friend of any sort, Cersei is more broken down than she wouldve ever imagined possible. The only thing that can possibly spare her is that which she dreads the most: confessing. To the lies, the affairs, the murder, essentially shattering whatever power it is she believes to have built around herself. Its a long way down when youre at the top, and no one has fallen harder or further than Cersei this season, and shes still got some way to go yet.