Well, it is obvious that all of them will be affected to a considerable degree. I'd vote for Sudha, Brij and KK for different reasons.
In Padma's case, I don't see why she would be shocked - having been exposed, and having burnt her bridges w/ Jyoti, she has nothing more to lose no matter what Jyoti does. If she expects Jyoti to continue funding the household - something that Jyoti plans to do but hasn't been doing of late - that would happen irrespective of whether Jyoti marries or not, particularly given that she now knows what Padma had been thinking all along. Nor will she be missing the joy of decking Jyoti up, since she hates her.
I agree that Brij is shocked, but I'm not following his thinking - after what he did to Jyoti, how exactly does he expect her to return to him? Just a few sorry's, like when he first tried disrobing her, and she firmly stopped him? I think he'll be disappointed that his plot has failed this time, but I don't think he'll be devastated, which is what I was implying above.
I think KK will be deeply saddened that Jyoti didn't think him worth informing, let alone inviting, although he will probably recognize that he has only himself to blame for this situation.
However, of all the family, I think Sudha will be the most devastated, given that the one person who loved her and looked after her well being is gone for good. If she becomes Devika, I wonder whether this time, it won't be for good? OTOH, Sudha can't just disappear - KK, Sandeep, et al would be on the hunt for her, and if Devika wakes up in the morning in Uday's house as Sudha, she won't know what's going on. This end needs to be tied up