Bani did say this to JAi after he apologised that she could have told him about Anu before, but she did not want to break Anu's trust in her.
I think it is very difficult to be a messenger in this case , how do you tell the concerned that your daughter is pregnant? Bani may have underestimated the problem at hand and thought it could be solved by abortion but in the hindsight she knows better...
Bani did what anyone in her mindset would do as first attempt to manage the situation even if it meant getting burnt in the process..
I think she was in denial that Jai would be so furious by her taking on the pregnancy blame.