The Oscar-winning actress died in her sleep on Sunday (15Dec13) at her home in Carmel, California at the age of 96, and de Havilland, who has declined to talk about her sister over the years, has now broken her silence about her longtime rival.
A statement from the actress says she is "shocked and saddened" by the news and grateful for "the many kind expressions of sympathies."
The late actress, who changed her last name from de Havilland to Fontaine so she wasn't confused with her older sister, was famously locked in a feud with her sibling for most of their lives.
In 1942, the sisters were both up for the Best Actress Academy Award. Fontaine eventually walked away with the prize for her role in Alfred Hitchcock's Suspicion.
In Fontaine's 1978 memoir, No Bed of Roses, she recalls the moment she heard her name called out at the Oscars instead of Olivia's.
She wrote, "All the animus we'd felt toward each other as children, the hair-pullings, the savage wrestling matches, the time Olivia fractured my collarbone, all came rushing back in kaleidoscopic imagery.
"My paralysis was total. I felt Olivia would spring across the table and grab me by the hair. I felt age 4, being confronted by my older sister. Damn it, I'd incurred her wrath again!"
De Havilland went on to win two Oscars of her own in subsequent years. The siblings eventually fell out for good in the 1970s, and 97-year-old de Havilland moved away from Hollywood to set up home in Paris, France.