Tesla CEO Elon Musk opened up about the death of his firstborn son in a 2018 email exchange that was recently made public with the parent of a driver who died in a Tesla crash.

“There is nothing worse than losing a child,” Musk wrote in an email to James Riley dated May 10, 2018, reports Business Insider.

In 2018, Riley’s 18-year-old son Barrett Riley and his friend died in a car crash when he lost control of a Tesla Model S going about 116 miles per hour and crashed into a concrete wall in Florida.

The series of emails was first reported by Bloomberg and is included in a court filing that was submitted in December in a wrongful death lawsuit filed by the family of Edgar Monserratt, the front seat passenger and Barett Riley’s friend who also died in the crash.
The thread of messages spanning almost seven weeks offers a glimpse into Musk’s personal involvement in customer relations around a horrific accident. He even brings up his own loss, one he has rarely discussed in public.

“My firstborn son died in my arms. I felt his last heartbeat,” Elon Musk wrote, referring to his son Nevada Alexander Musk who died when he was 10 weeks old