He wasn't thinking of being smart or tactful at all. He just let out what his raw feelings were, that he'd been trying to put a lid on since he saw Esha again.
I watched the scene twice and clearly he was talking about how he felt then that she was his soulmate and perfect partner so when she left him it broke him. The thing is, he hasn't moved on from that feeling of betrayal and that won't happen until he forgives her because he'll keep letting his hatred cloud his judgement.
In the dining table scene, even if it was just a couple of lines, he made it very clear where Esha and Pallavi stood in his life. I'd use that as a point of reference.
Also consider this. What if Raghav had been a widower? Would him talking about his first wife as being his perfect partner and soulmate bother us that much?
This track is reminding me so much of Punar Vivah where the ML was a widower who loved his first wife like crazy. He remarried for the sake of the kids but over time he fell in love with her too. He didn't stop loving his first wife and the second one made a different place in his heart. It's not about replacement.
In Esha's case it's a bit different because she betrayed him (or so he thinks), and she's still alive. Raghav loves Pallavi and considers her to be his present and future. Once he gets closure after finding out the truth about Esha, His current memories of their time together have been colored by her betrayal and have made him question his self-worth in terms of money and status and he doesn't want to be sucked into that quicksand again. The day he knows the truth, the memories will be colored differently and he'll be able to move on. I expect he will just remember her as a memory of the person who shaped his present and future.
Anyway, this is my read of the situation but I respect that people have different interpretations.
I am commenting here only about the Punar Vivah part here. Yash didnot two time Aarthi. He was very clear in his stance that he would not touch her nor was she his wife , except for legal purposes. I think he even asked to refrain from mothering his children. He never called one his soulmate and proposed love to the other. That's two timing. Aarthi knew Yash was a widower. Did Pals know that Raghav had an ex? Raghav didnot know Pallavi was a widow due to his own poor investigation techniques, she made no attempts to hide it. Shouldn't Raghav be forthcoming about his past affairs when he knows it would affect his future? Calling your dead /living ex your soulmate when you a present living wife is not done. It means disrespect to your current one. Pallavi never said she loved Mandaar. If she would said that, the whole FD would be in uproar now. Why is this partiality being shown to her? Because she's a woman?