There were executions she carried out on behalf of the regime because it was expected of her. It was imperative to her survival that she carry them out as ordered. She wouldn't regret those. Survival wasn't always possible without getting one's hands dirty. She was no martyr. Hadn't she proven since she was in Hogwarts that she would do what was necessary to keep those she cared about and herself protected? Any refusal on her part would've ensured her death and the death of her family. Not even Antonin would've been spared. He would've made the perfect example. So no, she wouldn't regret those deaths by her hands. Even Andromeda's death had been necessary. If she'd told her husband her worst secret, she would've been dead. And her husband knew how to make it hurt. She wouldn't shed a single tear over that wretched bitch's death. If the roles had been reversed, Andromeda would've been just as brutal.