Simon Barnett is taking extended leave from his hosting role on More FM Breakfast to care for his wife Jodi, who has been diagnosed with two lesions on the brain.
She is to undergo surgery to remove the lesions and doctors are said to be positive about her outlook.
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Simon, or 'Si', had been absent from his MediaWorks radio show for some days without explanation, with his co-hosts waiting until Tuesday morning to inform listeners of the sad news.
Co-host Gary McCormick described Jodi's illness as "a nasty shock" for everyone.
"Jodi appeared to have a massive fit, or stroke. This was very alarming for the entire family, to say the least. It was horrendous," said Gary.
"She went to hospital immediately and has since been diagnosed with two lesions on the brain. The good thing about this is that they're operable, and the doctors are positive about her outlook.
"She'll be having a major operation, but Jodi is a very stoic person - very brave... we hope Jodi will have this operation in the next 10 or 12 days. Then things will start to improve for the entire family.
"We all know Jodi, we all love her and this has been very distressing for everybody... I'm sure you'll join with me in keeping the entire Barnett family in our thoughts and prayers, and wishing Jodi a full and speedy recovery."
MediaWorks has also released an official statement.
"We are devastated to hear the news of Jodi Barnett's illness," said Leon Wratt, MediaWorks' Group Content Director of Music.
"While she remains in hospital to receive treatment, Simon will be on extended leave to support Jodi and his family through this very difficult time.
"On behalf of everyone at MediaWorks, we extend our heartfelt support to Jodi, Simon and their family and wish her a full and speedy recovery."
Jason Mac will cover for Simon while he is away joining Gary, Bondy and Sam with Lana joining the breakfast show as planned on Monday, May 14.
In 2017, Simon announced he would be leaving his job at More FM at the end of this year.