‘The Bachelorette’ Star Katie Thurston Announces Breast Cancer Diagnosis

Katie Thurston‘s sharing a major life update … telling her fans she’s been diagnosed with breast cancer — and, she plans to share every bit of it.

The ‘Bachelorette’ star shared the news in an Instagram post Saturday morning … telling fans she and her fiancé, comedian Jeff Arcuri, planned to travel the world before settling in NYC — but, they had to cut it short so she could deal with getting medical coverage for her illness.

She says her recent life has run her through a gauntlet of emotions … from anger, sadness to denial — before she emerged on the other side ready to fight cancer.

She ends her message by shouting out Arcuri … telling him she doesn’t know where she’d be without his selfless nature — adding “The selfless love that you smother me in is beyond anything I imagined I’d be blessed with. I love you to the fullest in this lifetime and the next.”

Katie was a contestant on season 25 of “The Bachelor” … and, though she didn’t wind up with that season’s leading man, Matt James, she was a fan favorite who got her own season of “The Bachelorette.”

She ended up accepting Blake Moynes‘ proposal … though the two ended their relationship months after filming wrapped.

Katie and Jeff met just last year … but, they instantly connected — and, he proposed on a beach just months later.