Dad hasn't told kids their mum died nearly two years ago
Lying in his bed, Zack has whispered "I'm sorry" to his bedroom ceiling almost 1,500 times in the past two years.
It's the first thing the UK dad-of-five says in the morning and the last thing he says before sleep.
He has no idea if his wife-of-11-years Cheryl, who passed away in January 2018, can hear him - but it's the only thing he can do to ease the guilt he feels over her death.
"I blame myself," the 37-year-old widow said.
"I think it was my fault that I spoke to her at half-past five on the morning she died.
"I didn't stay in bed when I should have done.
"Two hours later, she was found."
Cheryl had given birth to a baby boy just seven weeks earlier and had been sick since the family visited in December 2017.
The couple's children knew that their mum wasn't feeling great.
But it was still "out of the blue" when their eldest daughter, Rhiannah, walked into her parents' room to find her mum unconscious.
Despite the paramedics' best efforts, Cheryl was declared dead 45 minutes after they arrived - leaving the family in a state of complete shock.
"I couldn't speak to anyone for about two weeks after it happened," Zack said.
"I refused to eat, speak to anyone properly, I just wanted to turn my phone off and disappear for about two or three weeks.
"I was a mess. But at the same time, I knew I couldn't give in because of the kids.
"I knew that they only had me and I had to make sure I had a brave face on."
Despite his intense grief, Zack knew he had to soldier on for his kids - Rhiannah, 11, Amirah, 10, Kameel, nine, Kesaar Mulla, seven, and Layla Mulla, five.
"So I decided to try to hide my sadness. But my kids seemed to know that I was really sad and on the verge of tears," he said.
"I told them that even though they couldn't make my sadness go away, they could do something important by comforting me with all their hugs. I think their hugs have helped them as much as they have helped me."
"This might sound strange to some people, but I've not told any of my kids that their mum is not coming back.
"I've never said it. At the moment, I don't think the time is right given how young they are.
"I don't want them to get distracted and I'm waiting for the right time.
"The time will come. Every time they mention Mum, I just say she's in a better place. I don't want them to get upset."
Zack is focused on being both mum and dad to his kids - including learning to braid Layla's hair ahead of her first year of primary school.
"She's been asking me for a while but I told her I couldn't do it," he said.
"I can just about put two elastics around her hair.
"But I watched a few YouTube tutorials and tried it on a dolly.
"It's not a fantastic job but I'm doing what I can do. She was pleased."
Zack is focused on making his wife proud of their family and keeping her memory alive.
"We look through memory books with all the photos of our trip to Disneyland Paris," he said.
"They go through that a lot, which is good.
"I thank her, I thank her all the time. I'll always pay tribute to her and mention her on social media.
"I wouldn't be here without her, she blessed me with the children.
"As far as I'm concerned, they're her kids and I'm doing everything in my life for her to make sure they're looked after and loved all the time."
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This originally appreared on Kidspot and has been republished with permission.