Summer House's Carl Radke Says Brother Died 'After a Lifelong Battle with Mental Illness and Addiction'

"Losing my big brother is something I never could have imagined, and the sense of loss is even greater," Carl Radke said

Carl Radke. Photo: Charles Sykes/Bravo

Summer House's Carl Radke is mourning the death of his older brother Curtis.

On Friday, Radke, who has starred on all four seasons of the Bravo series, revealed on Instagram that his brother died after a "lifelong battle with mental illness and addiction."

Bravo did not immediately respond to PEOPLE's request for comment.

"Thank you to all my friends and family and extended family for the ❤️ and support over the last couple weeks. From the bottom of our hearts it means so much," Radke, 35, began.

"I know everyone sees me living my best life on reality TV, and I’ll be the first to admit I have been blessed in many ways… but today I want to remove the 'lens,' so to speak, by sharing something extremely personal with you," he continued.

"A couple of weeks ago, my brother Curtis passed away after a life-long battle with mental illness and addiction," Radke wrote, expressing that losing his "big brother is something I never could have imagined, and the sense of loss is even greater."

Radke went on to share sweet memories of Curtis writing that he had "an amazing sense of humor."

"The quotes and silly scenes in movies that we would share are still making me laugh. As children of the 90s, we both lived through the DARE campaign," Radke wrote.

Radke explained that his brother's death has pushed him to "break the stigma around mental illness & addiction."

"As I reflect on Curtis’ legacy, I think of his huge heart and passion for life. I know he would want to transform tragedy into something uplifting. I’m making it my mission to bring some light to one of the darkest experiences I’ve ever faced… and contributing something in my brother’s honor," he continued.

Radke then revealed that he will be "helping" a new company called More Summer Fun "which is all about maintaining warm vibes even during the 'stormy' seasons."

"From now through Mental Illness Awareness Week (October 4-10), 50% of all proceeds from MSF products will be donated to the Gaiser Addiction Center, where my brother sought treatment throughout his life."

Radke shared: "The person with the highest cart checkout for MSF products at the end of Mental Awareness Week will win a day with me in the Hamptons (exact date TBD, and of course, COVID depending). PLUS, I will personally be matching the total donations."

Radke concluded his post by sharing words of encouragement to his followers.

"Weathering the storm is far easier when you're surrounded by warm energy and good people. So let's act like it, beach. Here's to transforming a year with lots of loss into something meaningful. More Curtis, More Life. ❤️" he wrote.

Radke's tragic loss comes after he opened up about his own personal battles back in June.

RELATED: How a Homeless Mom of 2 Beat Addiction and Now Helps Thousands Going Through the Same Battles

“I stopped drinking in March," Radke said on an episode of The Publyssity Podcast,. "I’ve been sober since. I feel great. Now here’s the thing …like, am I saying I’m never going to drink again? I’ve never said. I just needed to take a break from it."

Radke said that watching himself on television made him reflect on his personal issues, most notably his excessive drinking.

“It’s been helping me take a step back and realizing I was drinking a ton and I was going out all the time," he explained. "A lot of my female relationships were affected. I didn’t know that until later on, by my drinking. I was running away from a lot of things I wasn’t addressing."

Determined to get healthy and happy, Radke sought help from a therapist — which he says has been a huge breakthrough for him.

“It’s my first time doing therapy while actually telling the 100% truth," he shared. "I’ve done therapy over the past six years and I never once, up until this past, you know, January, said I drink a ton. I’ve done drugs. I’ve partied. And it was liberating actually opening up with this therapist who focuses more on alcohol and just being completely honest."

If you or someone you know need mental health help, text "STRENGTH" to the Crisis Text Line at 741-741 to be connected to a certified crisis counselor.

If you or someone you know is struggling with addiction, please contact the SAMHSA substance abuse helpline at 1-800-662-HELP.