Kelly Clarkson’s ex-husband, Brandon Blackstock, reportedly spent the last few months of his life at his $1.8 million Montana Ranch while silently battling cancer.

“Brandon lived a pretty quiet life in Montana. That was how he liked it,” an insider told Us Weekly Saturday.

“Even though he worked in entertainment in the past, that was not his personality. He was at home in Montana.”

“He had his ranch and rodeo, but he preferred to go under the radar,” the insider explained.

“Some of the people who worked with him at Starstruck [Entertainment] ended up moving to Montana to work on the rodeo with him.”

Blackstock, who was 48 when he passed away, was already at his countryside home when his health “took a very bad turn” earlier this year, per the source.

The insider explained that the former talent manager “was focusing on his treatment” and had “spent a ton of time with his family in the last six months, more than ever before.”

His ex-wife Kelly Clarkson reportedly joined their kids, River, 11, and Remington, 9, in visiting him and made quality time with him a priority.

The source, however, noted that the “Breakaway” songstress, 43, “was not caring for Brandon.”

According to the insider, Blackstock’s eldest daughter, Savannah, 23, whom he shared with his first ex-wife, Melissa Ashworth, was “with him almost all the time.”

“She has been having an incredibly difficult time. They were very close. Everyone is in shock,” the source said.

“Brandon was traveling and doing things,” the insider added. “Even a few months back he looked okay. He looked thin but he looked like himself. No one can believe it.”

Blackstock also shared his eldest son, Seth, with Ashworth, to whom he was married from 2001 to 2012.

Reps for Blackstock weren’t immediately available to Page Six for comment.

The businessman died on Thursday after battling cancer for more than three years, Page Six learned.

Clarkson, meanwhile, noticeably stepped in and out of the spotlight, including by being absent from her morning show and canceling several of her Las Vegas residency shows amid her ex’s illness.