Bill Gates wrote in his blog on Tuesday that 2021 was the hardest year of his life as a result of his divorce with Melinda French Gates and the COVID-19 pandemic.

The Microsoft cofounder opened up in his year-in-review post on GatesNotes about the struggles he faced over the past year, including ending his marriage with Melinda after 27 years.

“I know a lot of people are curious about a subject closer to home: my divorce,” Gates wrote in the post.

The couple announced they were splitting up in May and were officially divorced in August, per court records.

Gates said he couldn’t deny that “it’s been a year of great personal sadness for me.”

The billionaire said that he and his ex-wife were still running the Bill and Melinda Gates Foundation, and that they’ve found a “good new working rhythm.”

It comes after the Gates Foundation announced in July that Melinda could step down as co-chair in two years if she and Bill cannot work together.

Gates said having days without any human interaction during the COVID-19 pandemic, was a “strange and disorientating experience.”

He continued: “My personal world has never felt smaller than it did over the last twelve months,” adding that he’s “officially an empty nester” after two of his children recently left home.

“I had stretches of time without any face-to-face social interaction” until getting vaccinated, he said. “If I had a break between meetings, I’d walk around my yard just to see something different.”

The philanthropist also faced criticism this year for his meetings with the financier and convicted sex offender Jeffrey Epstein — a relationship which Melinda warned her husband about, according to sources who spoke to The Daily Beast.

The New York Times and The Wall Street Journal reported in May that Gates had engaged in conduct at work that was deemed inappropriate, before his divorce.