Expecting Abhinav to feel guilty for keeping Abhir's truth away from Abhimanyu is unfair. He knows first hand how Abhimanyu rejected Akshara and the kid on that phone call. If anything, I absolutely hated the way he was being all chummy with Abhimanyu. Wouldn't you feel angered when you face a a person who treated your current wife(even if it is only on papers) and best friend, your only family, horribly in the past? He has seen the state of vulnerability Akshara was in the dau he met her. He has witnessed the pain which she has finally overcome after years and years of hard work. Come on, guy! This is not what what expected from you.
Also, I have come across some opinions that Abhimanyu's self pity is his redemption in itself. NO . It is not. The first step to redemption is to acknowledge the mistake you made, in its entirety! Not bits and pieces of it. And the guy who is not acknowledging the full extent of his mistakes to even himself, is far away from the path of redemption. Being miserable as a consequence of your own doing is not redemption. It starts by accepting to yourself and then to the person who you wronged that "yes, I f*cked up". Not some half as*sed excuse where you say "hey , you know that one sentence that I said? Which probably takes the lowest position in the long list of horrible things I said to you? I'm kinda sorry for saying that, okay?" and then wallowing in self pity and victimization that I wasn't instantly forgiven for a mistake that I did not even fully admit to , is absolutely pathetic to watch. Reflect on your behavior and try to do right by the person you wronged.