Yehuda reaches the climax of his speech to Yosef
כִּ֤י עַבְדְּךָ֙ עָרַ֣ב אֶת הַנַּ֔עַר מֵעִ֥ם אָבִ֖י לֵאמֹ֑ר אִם לֹ֤א אֲבִיאֶ֨נּוּ֙ אֵלֶ֔יךָ וְחָטָ֥אתִי לְאָבִ֖י כָּל הַיָּמִֽים. וְעַתָּ֗ה יֵֽשֶׁב נָ֤א עַבְדְּךָ֙ תַּ֣חַת הַנַּ֔עַר עֶ֖בֶד לַֽאדֹנִ֑י וְהַנַּ֖עַר יַ֥עַל עִם אֶחָֽיו.
For your servant assumed responsibility for the boy from my father, saying, 'If I do not bring him to you, I will have sinned against my father forever.' So now, please let your servant stay instead of the boy as a slave to my lord, and may the boy go up with his brothers
This is the end of the stories of Yosef and his brothers. To be more precise ,it is the beginning of its realization in our history. Only now, after Yehuda assumes responsibility, can Yosef reveal himself to his brothers.
What does it mean to assume responsibility, and why is this the game changer?