"What was she supposed to tell the Jewish priests"
Are you saying Mary lied to the priests about the birth of Jesus?
Are you suggesting she informed the whole world that +Joesph is not the father of the Child? Do you think she announcned that her Child is God Incarnate, conceived and born in a supernatural way?
She said no such thing because no one asked her. Everyone presumed the Child was +Joseph's and was no different than any other human child, including the way He was born, and therefore His Mother was considered "unclean" for 40 days, as any mother would be in the Jewish custom of the time (and in the Eastern Orthodox Church).
She knew the repercussions of such candidness.