Return for Revenge 

When Empress Sawol was pregnant with the Emperor's child, she loses all of her loved ones and then is sentenced to death by the Emperor and her little sister, who became the imperial consort. After her death, she magically gets another chance to relive her life. Will Sawol do the right thing when faced with her past mistakes and save herself and her family? And will she be able to take on revenge against the malicious Emperor and her sister? (Source: Lezhin US) Note: Chapter count includes a prologue.