The pair, who wed in 1999, and have a five-year-old daughter separated three years ago, but she has only now gone public on the spilt.
"We made the decision to separate three years ago and currently enjoy each other's respect and friendship.
"We have a healthy co-parenting relationship and our priority is, and will always be, our beautiful daughter," the 43-year-old said.
Mr Cantrell has moved out of their home in Clontarf but continues to share custody of their daughter.
The spilt took place around the same time that the blonde presenter became a permanent fixture on RTE News Six One.
A source close to the Montrose star revealed: "It's been fairly well-known in RTE for the last few months but I was surprised to hear they broke up so long ago.
"Sharon is just getting her head down and concentrating on her work, presenting the news every night.
"She obviously didn't want to bring her personal life to work and you have to admire her for that."
The source added: "She has been a real pro about the whole thing and hasn't been wallowing in pity or anything like that. She's very upbeat."
The perky presenter began her RTE career on Nuacht 14 years ago before moving to News 2 in 1997.
However, unlike some other TV presenters, Sharon has generally shunned opportunities to bring her family into the spotlight.
In a rare interview after becoming a mother in 2002, she said: "I've no time. I've zero time for myself, everyday is just frenetic, but you just get by. At the risk of sounding smug, I've never been happier.
"My husband berates me for not having more discipline but, hey, if she wants out of her cot at 4am to watch Tellytubbies, I just can't argue with her."
According to an RTE insider Sharon "is handling things well".
"This may come as a surprise to viewers and a few colleagues but her close friends and family have known about it for a long time."
The insider added: "Sharon is just a very private girl and doesn't like her personal life to interfere with her work."
After confirming that her marriage has ended, Sharon has asked for "privacy on this personal issue from my media colleagues". A spokesperson for RTE said this morning said that the station "will never comment on any personal issue relating to a staff member".