"[Divorce] was completely opposite to what I wanted. Really not," Rossdale, 51, told Fabulous, the magazine of British newspaper The Sun. "But here we are."
"Apart from death, I think divorce is one of the hardest, most painful things to go through," he said.
Rossdale admitted that that he has regrets and wished he could have done things differently.
"I know we all wish that, but we can’t, so I have to deal with reality," he said. "You can’t not have regrets and be human at the same time."
What he doesn't regret are the 20 years he spent with Stefani and their three sons, Kingston, 10, Zuma, 8, and Apollo, 2.
"We had 20 years together and that in itself is pretty incredible. It’s a lifetime," the Bush lead singer proclaimed. "I still think she’s incredible."
"It was a lovely 20 years and we have three amazing children," he continued. "There were a lot of positives, and with time they’ll become more and more obvious."
"The one thing -- the only good thing, because everything else is not good -- is we care about the children and it’s about them," he said. "So we do everything to make this life change as seamless as possible."
Rossdale and Stefani announced the end of their 13-year marriage in August 2015.