Brin filed for divorce from Shanahan in January due to irreconcilable differences, according to court documents filed in California seen by The Journal. He did so several weeks after discovering the affair, the publication said.

The two billionaires have been friends for many years, with Brin providing about $500,000 of funding for Tesla in 2008, when the company was struggling financially, the Journal said.

Musk reportedly dropped to one knee in front of Brin at a party earlier this year to ask for forgiveness over the affair, it added.

Musk, Brin and Shanahan did not immediately respond to CNN Business when reached for comment. Shanahan's divorce lawyer also did not respond when contacted.

Brin stepped down as president of Alphabet (GOOGL), Google's parent company, in 2019. He founded the search engine in 1998 with Larry Page. Both Brin and Page continue to serve on Alphabet's board.