At the end of his life, Vader’s final words to Luke are: “Tell your sister, you were right.” Before confronting their father, Leia told Luke she believed there was still good in Darth Vader and that he could be brought back to the light — the same thing their mother told Obi-Wan Kenobi in her final moments. Both women were right; Through the undying love of father, son, and daughter, Vader — Anakin Skywalker — was redeemed.
Leia had to face her dark family history in the years after the fall and rise of the Empire. By then, it was widely known that Luke and Leia were brother and sister, but their relation to Vader was a pretty well-kept secret … until it wasn’t.
The moment the galaxy found out they were the children of a Sith Lord nearly ended Leia’s political career. She accepted her heritage and continued fighting for the good for the galaxy throughout her life.