You would forgive the Nazis for the genocide of your people?
No. Of course not!
The old woman is right and very wise. Hatred and feelings of revenge are corroding to the soul and in the end poisons only yourself and not your enemies. She made it clear she does not forget. But she harbors no hatred in her soul for the Nazis because she has truly forgiven them. And I think that is what she meant by that being the key to her survival and happiness in her life.