Nick Cannon Details the 'Guilt' He Feels After Losing His 5-Month-Old Son Zen to Cancer

"I wish I could have done more, spent more time with him, taken more pictures," Cannon says of his time spent with his son, Zen — who died on Dec. 5

As Nick Cannon grieves the loss of his 5-month-old son, feelings of "guilt" continue to set in.

In an exclusive interview with PEOPLE, the TV host — whose son Zen, whom he shares with Alyssa Scott, recently died of a brain tumor — reflects on the short time spent with his youngest child.

"My heart is shattered," Cannon, 41, tells PEOPLE in this week's issue. "I wish I could have done more, spent more time with him, taken more pictures. I wish I could have hugged him longer."

Expressing such vulnerability is unusual for a usually upbeat Cannon, who first revealed the tragic news on his daytime talk show Nick Cannon on Dec. 7.

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"My goal is to make everyone smile every day and to forget about their worries, so at no moment did I ever think I'd be crying on live television," he says. "I really believe you can't heal until you feel."

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Cannon's youngest and seventh child, Zen, was diagnosed with high-grade glioma in August.

High-Grade Gliomas are tumors found in the brain and spinal cord. "These tumors can grow and spread quickly," says Dr. Joffre E. Olaya, a pediatric neurosurgeon at Children's Hospital of Orange County who treated Zen. According to Cincinnati's Children's Hospital, they are rare, accounting for 8 to 12 percent of all childhood brain tumors, and their cause remains unknown. Adds Olaya: "They are very difficult to treat."

Doctors placed a shunt in Zen's skull to allow excess fluid to drain and alleviate pressure, but they discovered that his tumors had continued to grow.

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Ryan Pfluger/August

"We started asking, 'Is there a way to prevent this? If not, how long do we have?' " recalls Cannon. "The conversations quickly turned to, 'How can we give him the best life for the time that he does have?' It could be weeks, it could be months, it could be years."

After discussing various treatments, including chemotherapy, Scott and Cannon — who has undergone chemotherapy himself for the autoimmune disease lupus — made the difficult decision to not pursue any further invasive procedures and focus on keeping their son "as happy as he could possibly be," says Cannon.

On Dec. 5, Zen took his last breath with his mom and dad by his side.

"I see it as a blessing that I got to be there," says Cannon. "Alyssa says, 'I think he was just waiting for you.' "

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While Cannon feels lucky to have been there with his son, he can't help but feel guilty.

"It's rooted in not having enough time to spend with my loved ones, specifically my children," says Cannon — who is also dad to 5-month-old twins Zion Mixolydian and Zillion Heir, whom he shares with Abby De La Rosa; 11-month-old daughter Powerful Queen and son Golden, 4, whom he shares with Brittany Bell; and twins Moroccan and Monroe, 10, whom he shares with ex-wife Mariah Carey. "I'm spread so thin in my work because that's how I deal with things."

"So much negativity comes my way because of my non-conventional acts and unorthodox [family] lifestyle," says Cannon, who has long gone to therapy to help with his daily struggles. "But I didn't want to hide anything."

So on Dec. 7 Cannon shared his heartbreak with his fans.

"Usually my world is jokes and satire and judgment, but it's been a complete 180 of nothing but love and people sending their well wishes," says Cannon of the support he's received. "It gives me hope in humanity."

Now Cannon and Scott are focusing on the good that came from their short time with Zen.

"He was the most loving baby," says Cannon. "I look at being his father as a great privilege."

Adds Scott via a written statement to PEOPLE: "It was a privilege being Zen's mommy. It's so beautiful and encouraging to see even complete strangers being touched and moved by Zen's light. Zen's spirit and light will shine bright forever."