Unfortunately Arivanya is needed for this quest to trigger, and there is a workaround but only for PC users.
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But the quest have 2 different workarounds:
If the Dragonborn accuses Wuunferth The Unliving to be the true identity of the "The Butcher", and he is locked away, Arivanya will be the next victim of "the Butcher" in the coming days.
However,
*** If the Dragonborn chooses to cooperate with Wuunferth and tracks "the Butcher" to his next crime scene
it's possible that Arivanya will appear as the next victim in which the Dragonborn may save her in the marketplace of Windhelm by killing the butcher before he stabs her.
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So, if you have killed her accidentally, go back to a previous save and choose the second *** workaround !!!!!
GOOD LUCK !!!!!