All The Darkest Truths by Avelyn Paige

Vesper Rossi was born into violence, but nothing could prepare her for the truth she now holds—a truth that burns hotter than revenge and cuts deeper than any blade. Her brother is alive, and her son—her stolen son—has been passed off as at the new Petrov heir, raised by her cousin as her own child.
With blood in her veins and fire in her heart, Vesper embarks on a savage journey to take back what’s hers. The Petrov empire will fall. Their alliances will shatter. And their very bloodline will burn.
With the Second Sons at her back and in her bed—Vesper will carve a path through anyone who stands in her way. She is no longer the captive; she is the storm, and she won’t stop until every lie has been scorched from the earth.
As Vesper tears through the underworld to rescue her brother and reclaim her legacy, the dark forces that stole everything from her are preparing to strike back. This is no longer about revenge—this is a war.
The truth will ruin them all. Blood will be spilled. And by the time Vesper’s vengeance is unleashed, the world will be nothing but ashes at her feet.