"They complemented each other very well in every way," said Diane's son Matt Whitfield. "I mean, it's just an example of two truly kind individuals that found each other, for whatever reason, and they just never stopped, always hung on."
On Mother's Day, the inseparable pair left Kathy's house to visit another friend. But they never made it.
Kathy's husband knew something was wrong when he called that other friend-who said Kathy and Diane had not arrived yet.
The California Highway Patrol says 24-year-old Sergio Mendoza Sanchez was drunk when he blew a stop sign and crashed into Diane's car at the intersection of State Route 137 and Road 60, killing both women.
"My two-year-old granddaughter ran through the house the other night," said Kathy's husband Jim Garges.
He said she couldn't find her grandma.
"How do you tell a kid that she's no longer here? Her world is upside down," he said.
Last week, the Tulare County District Attorney's Office charged Sanchez with four felonies, including two counts of gross vehicular manslaughter while intoxicated.
Prosecutors say he was also driving without a license.
He faces twelve years in state prison if convicted of all the charges.
"The penalties need to be more severe, and we need people to know who our mothers were," Whitfield said. "Many people knew them, but we need them to know this story, so maybe some person, somewhere, will take notice of this and maybe not get in the car drunk."
"It's happened too many times, and it needs to be stopped," Garges said. "Justice needs to look at our side instead of their side."
On Wednesday, friends and family of both women were in court for Sanchez's court appearance.
Kathy's husband and Diane's children asked the judge to hold Sanchez without bail, or at least set it at a higher amount.
They fear that if Sanchez posts bail, he will run away, and never be punished for what he did.
After hearing their pleas, the judge said he would decide on Friday.
To read more about the lives of Garges and Whitfield, click here: