No, she stopped herself from killing, after she figured out that she didn't really want to.
No one ever had her on a leash. She's killed before and gotten away with it, and Babs knows she's killed and still kept her around and took care of her as an agent. Helena gave up the homicide entirely of her own free will, and in fact did it in the same breath as a complete rejection of Babs, after which she went off to be a solo nonlethal asskicker accountable only to herself. Whether Bruce or Babs is looming over her shoulder is completely unrelated to her moral decisions.
And Babs is very much around, she's the one who put Helena on Man-Bat's trail.