Yes it was stupid anu who brought shaan to the sehgal house. But then Vish was pretty adamant that she was in love with Shaan. With that she put Bella and the other Naaglog in jeopardy. That was why she was fighting with Vishaka because she put her naaglog in danger. She was exercizing her power and authority as a Naagrani in the right place since as a Naagrani that is her duty and responsibility to punish those who's done mistake.