Where does the Wife of Bath interrupt her own story?

The Wife of Bath interrupts her story to tell the tale of King Midas, beginning by saying "we wommen" can't keep any secrets. To illustrate this point, she begins to recount the story of King Midas's wife. King Midas had long ass's ears, which he was able to hide from everyone but his wife. He asked her not to tell anyone, and she promised to keep his secret. However, being a woman, it burbled up inside her, and she thought she would burst if she didn't tell it somehow. Therefore, she went to a marsh and putting her mouth to the mire, she told the secret to the water. What happened next? The Wife of Bath tells her listeners to look it up in Ovid.
The Wife of Bath is being characteristically wise and cunning here. She begins a story about a woman who couldn't keep a secret, but she keeps the ending a secret—undermining the sexist point of the story she is telling!
In a story meant to show that women want and are deserving of having power in marriage, it makes sense for the Wife of Bath to tell a story within a story in a way that undermines sexist myths about women.

The Wife of Bath interrupts her own story after commenting about the knight's failure to determine what women really desire in life. She discusses what various women tell the besieged knight. 
Some tell him that women desire wealth, beautiful clothes, or a satisfying sex life. Others tell him that women desire freedom to live as they please. Yet others desire to be known as infallible, dependable, and discreet. At this point, the Wife of Bath questions whether women have the ability to keep secrets. She digresses from her tale to talk about King Midas and how his own wife couldn't keep his embarrassing secret.
Accordingly, King Midas had the ears of an ass, and he was profoundly ashamed of them. He begged his wife to keep his secret, and she promised him that she would be discreet. However, it wasn't long before she whispered King Midas' secret to the waters off the edge of a marsh. The Wife of Bath interrupts her story about the knight to tell the tale of King Midas and his terrible secret.