Anyway to keep it short, I know the forum is full of Milsi sypathisers (count me as one too) and Shabbos' realistic potrayal of it only makes it more painful for all of us.
But as I see it there seems to be some poetic justice to it all. Since Milsi himself believes in destiny and fate a lot, I would put it down to his punishment for the treatment he meted out to Prachi for so long for no fault of hers. See life teaches us the hard way. When we may get away doing something bad, the punishment may come to us for something we may not have done. Thats how justice is served.
Milsi never really suffered for all that he did to Prachi. The poor girl even went through a near rape for his misplaced beliefs. He may have a hundred and one justifications for his actions. That does not reduce the pain the girl had to go through, does it? But the minute he relented the girl readily forgave. In fact she forgave him even before that. He did'nt have to go through any torture (except may be a sense of guilt).
Now he is going through the torture and pain for no fault of his (although I would'nt say he cannot be faulted at all because he is suffering also because of his lack of trust) not that it was Prachi's way of getting back at him. Prachi too has her own justification for this (that she wants to spare him the pain of knowing about his sister). You may not agree with her logic much as I would not agree with the logic that makes Milsi think that Prachi is having an affair with Neev, but that is her logic.
So at the end of the day both Mi and Chi have wronged each other and they are paying for it. The only ones who are paying for all this without committing any mistakes are poor hapless Michians like us. For whoever is hurt the pain is ours. Our only fault being that we love these two duffers to the core.
About Shah clan not caring, I would'nt agree with you fully. The first thing PL said after Prachi told her lie is what would Milsi feel. You are the world to him. Dont do this to him for loving you. Now that did'nt seem insensitive to me. She has repeatedly been telling Prachi to tll him the truth. Even at the court house she urged her to tell the truth. It is another matter that Prachi is stubborn. Dont blame PL for that. Why this lady was so worried for Milsi when on the night of SS marriage she was telling Dadi she feared Niharika will create trouble for Suki. Milsi cannot ask for a more loving and caring M-i-l. Since she could not get her stubborn daughter to open up she was asking god's help through that Puja. What was wrong in that?
As to the rest of the clan standing by Prachi, what were they supposed to do, given that Prachi refuses to open her mouth? Cheer Milsi and tell him go for the divorce? Moreover, whoever is at fault, in the Indian society it is much more difficult for a woman to survive a divorce than a man. So they were there to provide their moral support to her. As to why they did not see his pain, as you have admitted yourself, this guy never shows his pain to any one and they are too thick skulled to understand that his anger is nothing but his pain.