She loved Brahma because he trapped her...
She is the most "Bechari" today because she not once but betrayed twice... After her first experience she is become strong... She has guts to kill her own husband but she knows Brahma is not Rishabh so to handle him and to reveal is real colors its to play back and do the same trick as He did...just PLAY and BETRAY.
She knows now the real Brahma and she even knows he can go to any level to make his life safe and the reason Baugi, Dev, Gaurav and even Priya can't do any wrong to him...All of them are scared... He won't mind even to trap his own son Adi...(Remember he once sent him to jail so that Priya can shut her mouth forever)
I think Uttara is playing with him so that ppl in the house knows the truth without harming anybody.