Kara Keough Bosworth welcomed her third child, son Vaughn Mack, with husband Kyle Bosworth on March 31

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Kara Keough
Kara Keough Bosworth
| Credit: Kara Keough/ Instagram

Kara Keough Bosworth — who recently welcomed son Vaughn Mack with husband Kyle Bosworth — is reflecting on the couple's "journey from our darkest day" as she marks the one-year anniversary of their baby boy McCoy Casey's death.

On Monday, the daughter of Real Housewives of Orange County star Jeana Keough commemorated the occasion by sharing a photo of herself holding McCoy in contrast with a picture taken from Vaughn's birth on her Instagram.

"Last year on April 12th, we held McCoy for the last time," Keough Bosworth, 32, began in the caption. "Remembering those moments will haunt me forever."

"Feeling robbed and grateful today as I also remember the moment Vaughn landed on my chest. Not sure I've ever experienced happiness like that," she continued. "That journey from our darkest day to the brightest hasn't been easy. But we kept going."

Kara Bosworth
Kara Keough Bosworth and husband Kyle Bosworth
| Credit: Kara Bosworth/Instagram

The star — who also shares 5-year-old daughter Decker Kate with Bosworth, 34 — went on to share how she dealt with grief in the past year.

"When people would say, 'I can't imagine what you're going through,' I tried to ignore that I'm living the unimaginable, and instead I focused on the fact that I'm 'going' through it," she explained. "It isn't stagnant. It's movement. We're headed in a direction. So we kept going."

"And when people would ask, 'How are you doing?' I'd reply, 'I'm doing.' Because sometimes, that's enough. In my case, that was everything," the mom recalled.

Whenever she felt "frenzied," Keough Bosworth found solace in focusing on "the next thing," she said.

"I'm so glad the 'next thing' was you, Vaughn Mack," she wrote in a note to her newborn child,. "You're not the next best thing; you're the best next thing. You're not a replacement; you're an extension. Thank you for making this April 12th so much better than the last, sweet boy."

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Keough Bosworth gave birth to McCoy on April 6, according to an Instagram post shared last year, with her son "weighing in at 11 lbs. and 4 oz., and spanning 21 inches." He died after experiencing "shoulder dystocia and a compressed umbilical cord" during the birth.

"McCoy surprised us all with his size and strength (and overall perfection)," she wrote at the time. "He joined our Heavenly Father and will live forever in the hearts of his loving parents, his adoring sister and those that received his life-saving gifts."

On Saturday, Keough Bosworth announced that she and her husband had welcomed their third child together, sharing that Vaughn was born on March 31 — just "6 days before what should have been his big brother's 1st birthday."

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"The day McCoy was born, I started writing a story. Our story. I don't typically like to spoil the ending, but in this case the ending is a new beginning," she wrote alongside a slideshow of photos of her baby boy

"Introducing Decker and McCoy's baby brother: Vaughn Mack Bosworth," she continued. "Measuring at 20.5 inches and weighing 7 pounds 6 ounces of heaven-sent sweetness."

According to Keough Bosworth, her Vaughn's name "means 'small/little' and 'hope.' "

"It's not lost on us that if we hadn't lost Mack, we'd never know Vaughn," she added. "And yet, here he is, an unexpected serendipity. A little hope."