Parshat Vayigash states, "And Yosef said to his brothers, "I am Yosef. Is my Father still alive?" (45:3) The Beit Halevi says that Yosef was being accusatory with this question.
As if Yosef was saying, after all you did to me, is my Father still alive? Didn't you realize the damage you would cause our Father when you told him I was killed? Yosef was not worried about himself. He was only worried about his father. His accusing his brothers as spies was to test them about their love of their father, whether they had remorse regarding the sale of Yosef, and their treatment of Binyamin.
The Ramban raises the question, " how could Yosef not send even one letter to his Father to inform him that he was safe in Egypt and to comfort him." This is a very significant question. The Ramban points out that Egypt was only six days away from Hebron. As Viceroy of Egypt it would have been relatively easy for Yosef to send messengers to tell his Father he was alive and well. The Ramban makes it clear that Yosef focused on his dreams and their fulfillment.
He knew his dreams would come true. He also had the foresight that his attaining the status of Viceroy was proof positive his dreams were going to be fulfilled totally and precisely. He could not waiver from his prophecy. Had he told his father that he was alive at the time he was appointed Viceroy, there was no way Yosef would have known that his brothers had done Tshuva (Repentance). He might actually have felt that they would still be interested in killing him.
He also had no way of knowing what kind of relationship the brothers had with their father, Yaakov at this stage of their lives. Yosef was a Tzaddik. He could not divulge his rise to power without first fully assessing the situation. He also did not want to endanger his brother Binyamin. He was afraid of the unpredictability of his brothers. He had no way of knowing whether they were remorseful till he put them through the series of tests that he devised. I am sure a day did not go by over 22 years that Yosef did not ponder what was happening with his whole family. It was only after he heard the words of Yehuda in Parshat Vayigash, "For thy servant became surety for the lad unto my Father saying, "If I bring him not unto thee then I shall have sinned against my Father forever"" that Yosef realized the Brothers had indeed changed and had done Tshuva.
They had been truly humbled. Yosef followed his dreams. He was steadfast. He united his brothers into one family unit. He did everything with a well thought out plan of action. This is part of his Righteousness. He could not inform his Father of his whereabouts till everything was in place. There were too many variables beforehand. He did not want anyone hurt. He could not gauge how his brothers would respond based upon his experience with them 22 years before.
It was a very delicate situation. He did not want his brothers (Shimon and Levi) to attack Egypt like they did Shechem. The prophecy directed his actions and in the end it brought about a reunification of his Family and relative tranquility for 17 years for his Father, Yaakov. Shabbat Shalom