@Zara Jazak Allah sister.. ameen..
I also have a sil like this so your not alone dw but may allah grant us good company i know the feeling too.
It's soo annoying.. why is hard to be nice.
I have noo clue sadly we live in time where being nice is rare people rather tear one other down
May Allah swt surround you with good company and protect you from bad company. Ameen. I don't think I have ever asked Allah for good company and He hasn't sent someone. Alhamdulillah