Google co-founder Sergey Brin filed for divorce after learning his wife cheated on him with Elon Musk — whose electric car company Brin backed during the 2008 financial crisis, according to a recent report.

The two tech titans were longtime friends. Elon Musk has said that for years he regularly "crashed" Brin's home in Silicon Valley — but then bumped into Nicole Shanahan last year, the Wall Street Journal reports.

Brin and Shanahan were separated but still living together at the time of their engagement in December, a person close to her told the Wall Street Journal.

Brin, who is worth $90 billion, filed for divorce in January, citing "irreconcilable differences." The decision came weeks after Brin revealed that Shanahan had been linked to the world's richest man, people familiar with the matter told the Wall Street Journal.

Brin also ordered financial advisers to liquidate his investments in Musk's various companies amid growing tension between the billionaires, the sources said.

In 2008, Brin gave Musk a $500,000 bailout fund for Tesla when the company was struggling to ramp up production amid the 2008 crisis.

Brin's attorney declined to comment.

Musk, a 51-year-old divorcee, fathered 10 children, the first of whom died of sudden infant death syndrome in 2002. Five of the other children were also born to his ex-wife , Justine Wilson.

Musk also fathered two children with Canadian singer Grimes — the second child, a daughter, was born through a surrogate — and earlier this month, he confirmed he had fathered twins with a director at his company Neuralink. The twins were born just weeks before his second child with Grimes.