When he confessed to Pallavi he did mention that he got drunk and very drunk. What I liked about his confession is for the first time, Raghav is hiding behind his defenses. What would he say, ki ok, I thought it was you but then it was Esha... Subah pata chala??
Waise bhi if he tell her that I imagined you, her pain isn't going to lessen. The truth that he knows and we know is Raghav slept with Esha. He's regretful and he's himself not able to come to terms of his deceit. How would he justify to her?
Thus, I liked the plain acceptance of his folly without any explanations. He faltered. He's taking the accountability og what he thinks / knows he has done.