Sister Wives' Kody Brown Says Relationship 'Could Have Been Better' with Son Garrison Before Death

In an interview with PEOPLE, the TLC star spoke about mourning his son, and expressed his sadness and regret that they didn't spend more time together before his death.

Garrison -- who was the fourth of six children Kody shared with ex-wife Janelle Brown -- passed away in March at the age of 25 following an apparent suicide.

Six months later, Kody, 55, said Garrison's death "still feels like a shock."

"The hard part is giving away that future that I saw for him, the excitement," he explained. "It's strange having your child pass. The wave of grief is different that any wave of grief I have ever had with a best friend passing, with a relative passing. It's different. And it is different in the idea that it's irreconcilable — the future that we missed with him."

Looking back, the reality star said that his relationship with Garrison "certainly could have been better" prior to his death.

"We could have been talking more. I'd get texts, stuff like that, and we could have, retrospectively, we could have done so much more," Kody told PEOPLE. "And it was almost like -- I'm busy with my life, he's busy with his life, and when we connect, we'll connect."

"It was kind of like, we've got forever. It was more like it was a convenience of time that I felt like I had," he said. "Retrospectively, there would've been more of a regular catching up and touching base."

The father of 18 said that Garrison's death has changed him "irrevocably," adding, "I can't get back to where I was. I can't reconcile that he's not here."

"You do have a little bit of an expectation -- and especially with somebody who's got essentially a bright future," Kody said. "He was planning a future. He always wanted a story to tell, some adventure. He was always either cracking a joke or wanting to talk about an adventure."

Ultimately, he admitted that he regrets not taking more "advantage of the time" he had with his son.

"I want to go out to dinner again. I want to sit down. I want to have a beer. I want him to try and make me laugh because he was kind of that way. The only regret is just, gosh, I would just do that more often," Kody said. "The only regret is that you didn't do something. You didn't take more time."

On March 5, Garrison was found dead in his home in Flagstaff, AZ from an apparent self-inflicted gunshot wound. No foul play was suspected. He was reportedly found by his 22-year-old brother Gabriel.

His death was ruled a suicide, according to an autopsy report obtained by Us Weekly.

In addition, the report showed that Garrison had a blood alcohol level of 0.307% at the time of his death, which is three times the legal limit. The legal BAC (blood alcohol concentration) limit is 0.08% or higher for people over 21. This is approximately four or five drinks for men.

Janelle confirmed her son's death on social media on March 5 with a post echoed on Kody's page.

"Kody and I are deeply saddened to announce the loss of our beautiful boy Robert Garrison Brown," they wrote. "He was a bright spot in the lives of all who knew him. His loss will leave such a big hole in our lives that it takes our breath away. We ask that you please respect our privacy and join us in honoring his memory."