The Napoli striker had his release clause of €90m activated by the Serie A champions on Sunday and is now the most expensive transfer ever between two Italian clubs.
Partenopei fans, former players and officials have decried the transfer, and now the club manager has weighed in with his opinion.
"It's hard for me to speak of Higuain after seeing him wearing the Juventus shirt," Sarri told Il Corriere dello Sport. "I'll talk about it, but not gladly. It was his own decision, because our offer matched what was offered away from here.
"From a personal point of view, I'm left embittered," he continued. "I was expecting at least a phone call, be it just five minutes before he had his medicals. But I'm old enough not to be surprised.
"The lads too expected a farewell. That I know of, there was nothing.
"But there's no use in crying over spilled milk. We're strong, and last year we played three games without him and made six points. I'd say that isn't bad.
"We lose a decisive player, the strongest striker in the world. In any case, I am Napoli's Coach and I must give [Manolo] Gabbiadini faith. He has means to be developed.
"We'll make good Higuain's absence by spreading out the responsibilities on the collective game. We haven't lost the desire to play the way we like."