"I couldn't help but laugh and think, 'My God, Diem's watching me right now,' " Tamburello tells PEOPLE

By Lanford Beard
Updated January 13, 2016 10:00 AM

More than a year after she lost her third battle with cancer, Diem Brown still lives on in the hearts of those closest to her.

Nowhere is that more clear than in Wednesday’s episode of The Challenge when Brown’s ex Chris “CT” Tamburello and her sister Faith return to pay tribute to the fan favorite and healthcare activist, who died at age 34 in November 2014.

“Diem approached everything in her life with bravery, courage and determination,” says Challenge host TJ Lavin in an exclusive sneak peek as he introduces Tamburello and Faith to demonstrate a challenge that brings back fond memories of Diem’s fearlessness and resilience.

In advance of his appearance on the show, Tamburello talked with PEOPLE about how it felt to return after his unexpected departure with Diem from Battle of the Exes II (they both exited when she was medically evacuated to address her failing health), how the tribute gave Faith new insight on her sister’s world and how Diem’s legacy has impacted his life – and many others’ – in the 14 months since her death.

This must have been emotional decision you. How did you know you should come back to the show?

Originally I was never going to do [a Challenge] again. I was over it. I don’t think it would have been right for me to just dive back into another show. I don’t think I was, honestly, mentally prepared to do it. But then I found out Faith was going to be on the show, and I feel like it turned out to be a blessing in disguise. For one, I felt like I was there with [Diem], being on there with Faith. Diem always called Faith her heart. For me to kind of poke my head out of my hole – you know, because I kind of went dark [this past year], and I didn’t want to do anything with anybody – to be able to come back on just to do a little guest spot, it was really nice. If I was going to come back on the show, I couldn’t have thought of a better way to do it than with Faith right there next to me.

And to come back this way must have been like a second chance in contrast to how abruptly you left the show last time.
I wouldn’t say second chance. It’s almost like a starting over. It’s a new chapter in my life now, and she was such a major part of my life. I feel like she would have wanted me to come back on. In a weird way, it was closure – not just for me, but for everybody that’s watched me grow and watched her grow and watched us grow together. For me to take that step forward, it meant a lot to me.

What was the experience like for Diem’s sister?
For Faith, to be able to see that side of her sister’s life, I think it went a long way for her. It’s hard to explain, the sort of camaraderie [on the show]. A lot of people knew Diem, and it’s almost like Faith met a bunch of close friends that she didn’t know Diem had. I know she was a little nervous – Faith is a little more of the shy type, she’s a little more introverted, she’s a sweetheart.

As TJ mentioned in his introduction, the challenge you and Faith demonstrated was very reminiscent of the Ring Toss challenge in The Duel I, which was a really powerful moment for Diem during her fight against cancer. That must have brought back some memories for you.

It was fitting. The mannerisms with Faith and that look she gave me like, ‘Oh my God, shut up, I’m going as fast as I can!’ … I couldn’t help but laugh and think, ‘My God, Diem’s watching me right now.’ Same old, same old, some things haven’t changed, you know?

Were you excited to see your old cast mates and the new competitors?
Not really. I was more excited to see Faith. In a weird way, I felt like it was the closest thing I could think of to actually spending time with D again. Faith was the closest thing to her heart – the way she talks, her mannerisms, the type of person she is. To be able to sit there and talk about back in the day, it was nice.

Have you embraced Diem’s spirit and the “Do it for Diem” attitude from this challenge in your own life over the last year?

Of course. She’s been a big influence on my life – not just me, but for everybody. For example, when they wanted me to come on and do this little guest spot with Faith, to me it was kind of a sign, like Diem saying, ‘Get up! Get off your butt! Move forward! You have to do this, get up!’ And having Faith do it with me made it that much easier.

And, not for nothing, what she’s done with MedGift – I’m so happy the way that Diem’s family has really taken charge of MedGift and continued to push forward and to try to make people’s lives better. That’s something that people still need to look into. If you really want to make a difference – that’s what I loved about Diem – go out and help people directly. Don’t just raise money and give it to some foundation where you don’t know where the money’s going to go. Go out and give it directly to somebody – and live every moment like it’s your last. Diem led by example, that’s for sure.

The Challenge: Battle of the Bloodlines airs Wednesdays (10 p.m. ET) on MTV. To help the Brown family carry on Diem’s legacy and her fight against cancer, visit MedGift.