Woman Says She Began Affair With Frankie Valli At 16

April Kirkwood has written a new book about her days with Frankie Valli that started when she was just 16 years old. INSIDE EDITION has her story.

The story of Frankie Valli and The Four Seasons is the subject of a big Clint Eastwood movie. Jersey Boys tells the tale of the legendary pop group from the '60s. There was nobody bigger.

But this is a story that you won't find in Jersey Boys.

At age 16, April Kirkwood talked her way backstage at a concert in Ohio and got to meet the great one himself, Mr. Frankie Valli.

Kirkwood told INSIDE EDITION's Megan Alexander, "He asked me to stay backstage, and after that he said, 'Would you like to go for a drink?' and I'm like, 'Yeah!"

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She says the inevitable happened. She says Valli took her to a local motel, and then took her virginity.

Alexander asked, "Do you remember what he said to you after that first night when you went home?"

"Yeah. 'Don't do this with anybody else, and always be a good girl,' " replied Kirkwood.

In April Kirkwood's 16-year-old mind, she never suspected she was just another conquest in a long line of pretty female fans who threw themselves at the star.

She says that night was the begining of a 20-year-long relationship.

In the new movie Jersey Boys, The New York Times movie review writes: "The Frankie of Jersey Boys turns out to be really nice, square and uncomplicated to a fault."

Well, maybe not, according to Kirkwood. She said, "I don't think it was right, what he did. And now I have to live with that for the rest of my life."

She says her mother was aware of the relationship and even put her on birth control and gave permission to tour with The Four Seasons. She was a groupie at age 16!

Kirkwood explained, "She took me up there, 'Good luck. Hi, take care of my daughter' [and he said,] 'I will. Don't worry, mom. She is in good hands.' "

Kirkwood has written about her days and nights with Frankie Valli in a new book Big Girls Cry. The title is a takeoff on a huge Four Seasons hit, 'Big Girls Don't Cry."

Of course, April Kirkwood and Frankie Valli never married. She went on to have a career as a teacher and have two children.

But after all these many years, Kirkwood says she's still in love with her first love, saying, "I made that very clear to everybody that he was the first, the one, and the only."