Serena Williams has had a roller coaster 2018.

Balancing motherhood with her prestigious tennis career since giving birth to her daughter in September, the 23-time Grand Slam champion has endured a post-pregnancy scare, postpartum depression, a pectoral injury that forced her out of the French Open, reportedly relentless drug tests and the worst loss of her career -- a 6-1, 6-0 decision at the Silicon Valley Classic -- in between triumphs like a runner-up performance at Wimbledon.

As the cover star of this week's Time magazine, Williams has revealed that her roller coaster was even wilder during that historic defeat in San Jose, where she didn't win at least two games in a match for the first time in her long career.

In fact, just about 10 minutes before Williams took the court that day, she learned that Robert Maxfield, the man she witnessed receive a 15-year prison sentence for the fatal shooting of her half-sister Yetunde Price in 2003, had been freed from jail. As Sean Gregory writes for Time, Williams learned through Instagram that Maxfield "had been released on parole earlier this year," and she's since reflected on how that discovery impacted her.

"I couldn't shake it out of my mind," Serena says. She laughs, which she sometimes does during uncomfortable moments. Price had three children, who were 11, 9, and 5 at the time of the their mother's death. "It was hard because all I think about is her kids," she says, "and what they meant to me. And how much I love them."

She takes a deep breath. "No matter what, my sister is not coming back for good behavior," she says. "It's unfair that she'll never have an opportunity to hug me. But also …" she pauses, the thought hanging in the air. "The Bible talks about forgiveness." Does she forgive the killer? "I'm not there yet," she says. "I would like to practice what I preach, and teach Olympia that as well. I want to forgive. I have to get there. I'll be there."

Williams, 36, will return to the court starting Aug. 27 in pursuit of her 24th singles Grand Slam title.