"She was a blessing and the light of my life".
"One thing led to another, and they started going together".
According to CNN, her death also notably comes out around two decades after her husband's, who died of a heart attack in 1998 at the age of 82.
Frank admitted, when questioned by Nancy, that he had been involved with another woman, but he insisted there would be no more and the pair got married. "He has a few times sought out Nancy Sinatra, even though she does not fit into the fast-moving, neurotic world he seems to prefer".
"She fought hard to remain on this earth but time got the better of her", she wrote, adding that her mother passed "peacefully".
Frank Sinatra left his Nancy for Ava Gardner in the early 1950s.
In 1934, Nancy Barbato met a young Frank when he was a relatively unknown jazz singer in Long Branch, New Jersey. "Godspeed, Momma. Thank you for everything", Nancy Jr. tweeted.
They began their marriage living in a modest apartment in Jersey City, where their two eldest children, Nancy Sinatra Jr. and Frank Sinatra Jr., were born.
The couple's first child, Nancy, who would go on to become a singer in her own right with the "60s hit "These Boots Are Made for Walkin", was born June 8, 1940.
After the gossip over the divorce and Gardner marriage died down, Nancy Sinatra devoted herself to family and numerous celebrity friends, largely withdrawing from the spotlight.
In 1966, journalist Gay Talese wrote of the couple: "There is no bitterness, only great respect and affection between Sinatra and his first wife and he has always been welcome in her home and has even been known to wander in at odd hours, stoke the fire, lie on the sofa, and fall asleep".