Going to the dark side. Carrie Fisher admits her 1976 affair with Star Wars costar Harrison Ford left her feeling vulnerable.

“It was sad because I was so insecure,” Fisher, 60, revealed on the Today show Monday, November 21, of her three-month tryst with the then-married father of two.

The actress, who played Princess Leia in the original Star Wars trilogy and reprised the role in last year's The Force Awakens, discusses the situation in her upcoming book, The Princess Diarist — a published version of her journals from her time filming the sci-fi series. “It's very raw and obviously I didn't expect anyone, including myself I suppose later on, to read it,” she continued.

The mom of Scream Queens star Billie Lourd (with ex Bryan Lourd), described her romantic involvement with Ford, now 74, as a “three-month one-night stand” that she felt guilty about. “I wasn't raised that way," Fisher said. "But when you're on location — this is something I discovered — everything is permitted."

In one excerpt, she explains that the affair began after Ford offered to drive her “wine-sodden” self home, and the two slept together. “I looked over at Harrison. A hero’s face — a few strands of hair fell over his noble, slightly furrowed brow,” writes the daughter of Hollywood legends Eddie Fisher and Debbie Reynolds. “How could you ask such a shining specimen of a man to be satisfied with the likes of me?”

Fisher even dreamed of the Indiana Jones actor leaving his wife at the time, Mary Marquadt, and proposing to her with a ring engraved with a hybrid of their names: "Carrison.” Though Harrison returned to his family when shooting in London wrapped, he and Marquadt divorced in 1979.

Now wed to actress Calista Flockhart, Ford received a warning from Fisher about her forthcoming book, out November 22. “I told him I had found the journals and that I was going to publish them,” Fisher clarified on Today. “He sort of went, 'Lawyer.'"

Still, the author feels shocked fans are interested in their affair. “I'm surprised at the reaction," she added. "I don't think it is that surprising."

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