The make-up artist, originally from the small town of Cappawhite in Ireland's County Tipperary, was found dead at her Los Angeles, California home Monday night, after two friends went to check in on her at the $1.1million residence.
White allegedly left behind a suicide note in which she mentioned breaking up with Carrey on September 24, according to TMZ. That's the same day that she wrote a worrying message on Twitter.
'Signing off Twitter, I hope I have been a light to my nearest and dearest,' White wrote.
Los Angeles deputy chief coroner Ed Winter said that a drug overdose is suspected because several pills were found near White's body. While the death is believed to be a suicide, an official ruling has not yet been made.
Scroll down for video
Jim Carrey's ex-girlfriend Cathriona White, 28, has committed suicide. Carrey and the Irish beauty pictured above in New York City in May, with Carrey sporting a jersey for the Irish hurling team from White's home county of Tipperary
White reporetedly left behind a suicide note, mentioning the fact that she broke up with Carrey again on September 24 - the same day that she tweeted this troubling message
Following news of his ex-girlfriend's death, Carrey issued a statement saying he is 'shocked and deeply saddened by the passing of my sweet Cathriona.'
'She was a truly kind and delicate Irish flower, too sensitive for this soil, to whom loving and being loved was all that sparkled.
'My heart goes out to her family and friends and to everyone who loved and cared about her. We have all been hit with a lightning bolt,' Carrey said.
I am shocked and deeply saddened by the passing of my sweet Cathriona. She was a truly kind and delicate Irish flower, too sensitive for this soil, to whom loving and being loved was all that sparkled.
Jim Carrey
Meanwhile, in England, Cathriona's mother Brigid Sweetman was too upset to talk about the loss of her daughter when reached by Daily Mail Online on Tuesday.
But a relative said she is planning to travel to Ireland later this week to be with family.
Sweetman moved to the UK from Ireland after divorcing the father of her three children.
White and Carrey first started dating in late summer 2012, but by March the following year they had fallen apart.
The couple appeared to have rekindled their romance this past May when they were seen happily smiling and holding hands on outings in New York City.
In one of the pictures of the couple taken in May, Carrey is seen wearing an Irish hurling jersey representing White's home county of Tipperary.
On Tuesday, the three-bedroom, $1.1million house where White's body was found had been sealed by the coroner.
The house has a swimming pool at the rear and spectacular views overlooking the valley opposite.
Family photographs can still be seen in one of the bedrooms, including one in silhouette that appears to be of White and Carrey. It is believed White was renting the property for $5,000 a month.
Cathriona White was living in America when her brother James was awarded the Military Cross by Queen Elizabeth II for heroic acts during his deployment to Afghanistan
Cathriona White was living in America when her brother James was awarded the Military Cross by Queen Elizabeth II for heroic acts during his deployment to Afghanistan.
The Irish-born man had always wanted to be a soldier, and decided to join the British army after getting first turned down by the Irish army, his father Pat White told the Irish Independent in 2011.
'He tried to join the Irish army, but failed on the medical because he had asthma as a child, but he quickly grew out of that. He worked here for a bit before moving to England and joined the army,' Mr White, now deceased, said.
A member of the Parachute Regiment, James was one of 136 members of the British Armed Forces chosen to be honored by the queen with a medal in 2011.
While James had served two seven-month tours in Afghanistan at that point, as part of a special forces support, it was his brave actions on his second tour that merited the medal.
The first happened when two platoons were pinned down by enemy fire, and James ran more than 200 yards in open ground to assist his comrades.
James is also said to have took out an insurgent machine gunner and helped evacuate soldiers taking causalities by attacking an enemy-held compound.
Meanwhile, the death no doubt comes as a hard blow for Carrey, not only because of his romantic relationship with White but because of his longtime battle with depression.
In a 2004 60 Minutes interview, Carrey revealed that he had been medicated to combat the disease.
'I was on Prozac for a long time. It may have helped me out of a jam for a little bit, but people stay on it forever. I had to get off at a certain point because I realized that, you know, everything's just OK.
'There are peaks, there are valleys. But they're all kind of carved and smoothed out, and it feels like a low level of despair you live in. Where you're not getting any answers, but you're living OK. And you can smile at the office. You know? But it's a low level of despair. You know?' he said
Carrey pictured above in April, around the time that he got back together with White
In addition to quitting Prozac, Carrey said he stopped drinking alcohol and pretty much nixed caffeine as well.
'I rarely drink coffee. I'm very serious about no alcohol, no drugs. Life is too beautiful,' he said.
Carrey has twice been married. In 1987 he wed Comedy Store waitress Melissa Womer; they stayed together for eight years and have a daughter, Jane Erin Carrey, the same age as White, who has a child of her own.
A year after Carrey's split from Womer in 1995, the actor married his Dumb and Dumber co-star Lauren Holly, but that marriage lasted less than a year.
After than he was involved in a number of relationships with other actresses including January Jones, Laurie Holden and Me Myself and Irene co-star Renee Zellweger, to whom he was briefly engaged.
In 2005 he began a five-year relationship with Jenny McCarthy, and became a step-father to her son Evan.
Carrey started out his career as a comedic actor in such Blockbuster hits as The Mask, Dumb and Dumber and Ace Ventura: Pet Detective before moving on to more serious work.
He has twice won a Golden Globe award for acting, for roles in Man on the Moon and The Truman Show.
His part in the cult film Eternal Sunshine of the Spotless Mind, in which he plays a man undergoing a procedure to erase the memory of an ex-girlfriend, has also become a career-defining role for the actor.
