What made Edmund realize that the with had tricked him into returning?

Edmund realized that the White Witch had tricked him into returning when he overheard her discussing her plans and intentions. He understood that she had manipulated him, playing on his desires for power and status, and that she intended to use him to achieve her own goals. The realization struck him that he was not a valued ally but rather a pawn in her scheme, leading to feelings of betrayal and regret.