Why does Bani?

Why does she asks Pia about the letter in public. I don't think she knows the truth behind thel etter yet. But still why does she want to public display of her sisters feeling even though for her husband Pushkar according to BAni?

That was so cheap of ekta.

If Rano is smart & connects PIa's monologue about apologising Bani & this letter, she will know whats going on & hopefully stop Pia from destroying BANi's life.