Not so soon! Dev cannot get rid of Barkha so soon even after he comes to know of her entire truth...because she has many weapons in her hand to destroy the entire RPti! First -- the lie Dev told by declaring an unwed Barkha as his RPtian. Second -- he chose to have his wife in his house but never declared her as one. Third -- the entire property belongs to Barkha. If she comes down to using these one by one against Dev and the family, they would come out on streets! Society would never accept Dev back as RP because he was a liar!
Plus there is this mystery person who is the mastermind behind Barkha.
So it would take some time. The layers would peel out only gradually. It has begun now as we can see...because Dev's blind trust on Barkha is no more there. He is doubting Barkha, and doubting on her openly. First he doubted on her during the bhoot drama, but hesitated to acknowledge it...however now he is openly saying it. Its an improvement. Apart from Dev, the only person who trusts her is Padma. Her belief too has to be shattered. Lets see how they proceed with all this.
With Kanha regaining back his powers, it should be more illusions for Barkha na? ;))
And Kanha doesn't want to give direct punishment to Barkha. Getting a punishment at once would be a far easy one for the cruel lady! But living in the fear that any moment her sins can be exposed, and any moment she can be thrown out from the house to the jail...is a far more worse situation. Every moment Barkha would be on her toes to keep herself safe, to plot and plan new things...new tricks etc. This would ensure that she cannot lead a peaceful life at all!!