Not only did she know about the Rejoinings when she left Emet-Selch alive, her plan hinged upon his actions and she tried to allow him a second chance to live because she felt bad about the part he was manipulated into playing. To say that Venat has basically no issues with sacrificing lives, whether directly or by proxy, is about as text as it can be at this point. If you find that abhorrent, then you find Venat herself abhorrent.