In the Torah, Joseph reveals himself to his brothers by saying "I am your brother Joseph." Despite all the things Joseph's brothers did to him, he was ready to forgive them.

It was actually not Joseph's revelation, it was his brothers' revelation... Joseph was such a genius, that he saw ahead to create the exact same situation between his brothers and Banjamin that he and his brothers were in years ago so that his brothers could either do teshuva (repent) or do the same as they had in the past. His brothers were willing to give their lives to save Benjamin rather than causing their father to grieve losing another child. Once they did this, Joseph forgave what the brothers had done to him.