i don't know how he killed her because i didn't watch the episode
i know he didn't kill her just because he felt like he killed her because she tried attacking his parents. If he had left her alive she would have came back with some other plan to kill the Raichands.
Abhay killing her has made the werewolves side weaker(as Chaand said in an episode she was the head of the werewolves)
I didn't like it🤔 maybe because it turned out to be really brutal her screams while dying really pinched my heart (and I am serious)...
Yeah the werewolves are weak now but now they are agitated , furious and angry..so now mentally they are stronger.