Lesley Gore, the singer of hits including “It’s My Party,” “Judy’s Turn to Cry” and “You Don’t Own Me,” passed away Feb. 16 at age 68.

Now — in an exclusive interview with ‘Closer Weekly’ — her longtime partner of 33 years, Lois Sasson, reveals new details about her sudden death and lung cancer diagnosis.

“It was pretty fast,” Lois tells ‘Closer.’ In January, “she had a pain in her back — she went for an MRI and we found this horrible tumor on her spine.”

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Lesley performing in 1965.

Lesley’s death may have come on quick, but her memory will live on for years to come.

“She was writing the story of her life,” Lois tells ‘Closer’ about a new stage show she was working on. “She would want to be remembered for the music and the play she was writing.”

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Though Lesley didn’t live to see that show produced, she lived a full life — from teen pop sensation to feminist role model and gay rights activist.

“She had a very rich life,” Lois tells ‘Closer.’ “She was a beautiful woman who was an icon and personified fun and lightheartedness, but she was also very serious.”

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Lesley performing in July 2011.

While she kept a low profile in later years, working behind the scenes as a composer of songs like Fame’s Oscar-nominated “Out Here on My Own” (co-written with her brother, Michael), Lesley had a major coming-out party in 2005 when she announced she was a lesbian.

“It was hard for her mother, but not for her,” Lois tells ‘Closer’ of Lesley, who came out privately to her parents in the 70s. “She was totally comfortable in her sexual shoes.”

For the full interview, pick up the new issue of ‘Closer Weekly,’ on newsstands tomorrow!