In 1926 Christie disappeared mysteriously for ten days. There was a massive search for her; and she was eventually found at a hotel in Harrogate. Some thought it was a publicity stunt, others that she had lost her memory under psychological stress. Her husband had just told her that he wanted to leave her for another woman. Until she was found, there were people who suspected him of having killed her. When I first read about it, the general view was that it was certainly a reaction to the stress of the impending divorce, perhaps with some attempt to embarrass her husband or his mistress, which is the line that Wikipedia currently favours.
In fact just four years after the incident, Christie published a short story, which reads like a confession to me; and it gives a picture of her actions much like what others have supposed. "The Affair at the Bungalow" (1930) is one of a series of short stories, later published in The Thirteen Problems (1932), in which guests at a party tell of mysteries they have experienced, and the other guests try their hand at solving them, with Miss Marple always finding the correct solution at the end.
For the rest, I can't avoid giving the plot to that particular story away. So stop now, if you care.
The narrator of "The Affair at the Bungalow" is Jane Helier, an actress. The mystery is a burglary, involving Helier tangentially, in which someone apparently impersonated the occupant of the burgled house, the owner's mistress. At the party the mystery is left unsolved. But we learn from Helier that Miss Marple has guessed that this was actually a plot by Helier to draw attention to the mistress, who had stolen her man. The mysterious burglary would inevitably lead to the press finding out the details of her life.
I wanted her shown up -- I would like everyone to know the sort of woman she was. And you see, with a burglary, everything would be bound to come out.
In the story, the idea is only a plan that Helier has not yet put into effect. For Agatha Christie, there was no way to go back. After her actions had had such success in throwing a spotlight on the people who had betrayed her, but also onto herself, she could hardly publicly admit to what she had been doing. But "The Affair at the Bungalow" was as near to a confession as she could get.