Sonakshi did wrong by telling the truth to Pooja directly and taking her to meet Rani.
She behaves irresponsibly as a person. also put herself and Pooja in danger. Come on how could she take the word of a person she just meet.
Behaved insensitivity as a family member towards Nishi&yk. Forget about Rohit for a moment here.
Giving birth to a child does not make you a parent but being responsible for the child what matters most when come to being a parent. They raised her and it's between them and Pooja.
There is no justification for interfering in their duty towards their child. Very insensitive.
I do believe When it comes to the partners Sona should have waited and discussed with Rohit first before starting this. In fact she should have tried harder to make him reveal the truth which she knew he was hiding.
Instead she chose to act in the moment just like the time she chose to go for the shoot without informing him during the wedding..
I feel she has insecurity issues with loved ones leaving her. Always testing him in some ways or other to prove to herself he will also leave.
A form of coping mechanism that will help her when the inevitable reality(in sona's mind) of him leaving her happens. . I feel Sona does not trust Rohit's complete faith in their love. She is scared of being deserted by him.
About Rohit telling Sona about a truth that is not his to begin with is just poor excuse. Remember Rohit fully trusted her during Matre track even though he knew she was not telling him the truth despite him asking her many times.
So Sona should have had faith in Rohit and waited for him to deal with the issue and maybe provided support which would have made it easier for him to share the truth.