I also suspected that Anshuman would only be making Pakhi look better with all his scheming and that is exactly what happened. He is doing for Ayaan what Lavanya did for him in the whole gift situation, making the former's expectations so low and scary that Pakhi's pure and warm-hearted sincerity shines even brighter. Ayaan has always been completely aware of Mahaji's hypocrisy, more than anyone else in the house. Before he used this knowledge to his advantage because he felt alienated and insecure but in this situation he sees that MJ is plotting against Pakhi when Pakhi only wants to do nice things for him. The fact that Pakhi is aware of Mahaji's hypocrisy and declared it loud enough for Ayaan to hear will increase his respect for her intelligence and low BS tolerance. It's as though everything is inevitably leading Ayaan to Pakhi.
Even the letter will serve this purpose because it will open up communication between Ayaan and Pakhi completely, the lack of which is the one weakness Anshuman and Mahaji have been able to exploit thus far. Ayaan and Pakhi are both too smart to fall for lies and they will definitely put the pieces together once they communicate openly. And once that happens, Anshuman is a goner!
As for the man himself, I have read a lot of disappointed posts about how he keeps going back to square one. I think the thing to remember is that he is not on some predictable, linear path here where he has to progress from bad to good. His mind is operating on two planes at this moment, one unconscious and one conscious. He doesn't realize how much he is unconsciously becoming Pakhi's husband while consciously trying to make her leave. It is only when his conscious goal is realized and Pakhi leaves that he is even going to be aware of everything he was unconscious of so far. As long as he can't win, he will want to but once he wins he will find that victory completely empty.
In fact the process has already started with his sister suffering the results of a similar betrayal. Girish could have told Lavanya about Naina's parentage right off the bat, but he didn't. He let her think that they were in this together, that adopting Naina was a way to make their lives complete. He let her get completely attached to Naina, become a mother as she said yesterday, and then told her the truth. Had he told her before, there is no guarantee that she would have forgiven him but it would have at least been one less loss. The way he did it now, she has to suffer the loss trust in her husband, the loss of her marriage as she knows it and the loss of her essentially "new-born" baby.
It's the same with Pakhi. Had Anshuman been honest at the beginning she would have lost a dream, that's it. Now she will lose a man she truly loves, her child and her family. TP is heartbreak central these days, potential and actual!