"I had my fair share of three days straight of just crying," Sills' widow, Ariana Sills told KTVU on Monday.
It should have been a celebration for the family, because her husband had just turned 31. But two days after his birthday, the father of their two children was shot dead.
"I'm doing the best that I can not to fold for my kids," she said "My kids are taking it hard but, more than anything, my son. He's not eating. He's sleeping throughout the day. He's not talking to anyone."
On the night of May 1, her husband left their 9-year-old son's baseball game as it was ending, saying he planned to pick up a pizza. But she grew worried when she didn't come back after half an hour had passed.
She tracked his location to the 7-Eleven on Hillcrest Avenue in Antioch and drove over with her kids. They were shocked to find the store and gas station blocked off and surrounded by police.
"Both my kids saw my husband's car, the doors open, and a yellow bag over it. So they saw everything. There was no trying to hide it," she said.
Antioch police said the confrontation likely occurred inside his Toyota Avalon, possibly outside a nearby restaurant or gas station. Sills ended up driving across Hillcrest and crashing at the 7-Eleven. Police say two men ran from his car.
"It's unfortunate. There's no question about it," Antioch Police Chief Steven Ford told KTVU. "One violent crime is one too many in my opinion."
No arrests have been made, and a motive isn't known.
"That investigation is being carried out in the most diligent of ways. Our investigative team is still top-notch. They're working hard," Ford said.
Now, the family is struggling to make sense of their loss.
"It's hard to grasp. It's unreal. It feels like it's - you're gonna wake up from it," said Kimberly Nieve, the victim's sister-in-law.
"He was ultimately the best father," said his wife. "I mean, he always provided for those kids."
Clayton Sills was the 31-year-old married father of two who was fatally shot in Antioch while buying a pizza for his family on May 1, 2023.
The two have been a couple ever since they met in Spanish class at Pittsburg High.
She had this message for those who were responsible.
"It really sucks that you, you know, destroyed a family. It sucks for the kids. Nobody ever thinks of the kids."
A Gofundme has been set up for the family.