I'm not sure I understand it exactly, and it is not common English phrasing. However, "viscera" are the soft organs in the abdomen, particularly the stomach and intestines; in less formal English, "guts." A "visceral feeling" means an emotional feeling, usually an unpleasant one like anxiety or fear, that is so strong that you experience it as a physical feeling in that part of the body; indeed, it may even have a actual physical effect. Examples of use of similar phrases include "I have a gut feeling about that," "a gut-wrenching experience," "a stomach-churning feeling," "I have butterflies in my stomach." In fact, the word "yearning" is a variant of "churning" and suggests a gut feeling. I don't know what's meant here by "visual betrayal" nor do I know why it would "therefore" be "a visceral betrayal."