The 23-time Grand Slam champion was stunned 6-1, 6-0 by Britain's Johanna Konta on July 31 in San Jose, California.
The defeat marked the first time in 928 professional matches that Williams failed to win more than one game. At the time she spoke of having "so many things on my mind" without elaborating.
But in a wide-ranging interview with Time, she said that 10 minutes before she took the court she learned via Instagram that Robert Edward Maxfield, the man convicted of killing Price in a drive-by shooting in 2003, had been released from prison earlier in the year after serving 12 years of a 15-year sentence.
"I couldn't shake it out of my mind," she said. "No matter what, my sister is not coming back for good behavior. It's unfair that she'll never have an opportunity to hug me."
In discussing Maxfield, Williams noted biblical passages on forgiveness, but admitted "I'm not there yet."
"I want to forgive," she said. "I have to get there. I'll be there.”
Price had three children who were aged 11, nine and five when she died.
"It was hard because all I think about is her kids, and what they mean to me. And how much I love them," Williams said.