Williams said Monday he takes full responsibility for his punt-return fumble, which set up Lawrence Tynes' winning 31-yard field goal in overtime Sunday night, calling the moment "painful."
"I really didn't pay attention to Twitter," said Williams, who was filling in for injured punt returner Ted Ginn Jr. "All the feedback I needed was family and friends, the guys in the locker room."
Instantly, Williams was made a villain on the Internet.
He insisted it's part of his job to face the criticism in the aftermath of his mistakes -- he also muffed a punt during the third quarter -- and not hide out in a difficult time. Perhaps that will go a little way in calming down the angry fans, some of whom wished harm on Williams and his family after the gaffes.
"It's one of those things you have to take accountability for," Williams said. "Everybody is responsible for what they do on the field. It's something that I was responsible for, and I made a mistake and it's time to own up to it and move forward."
Niners kicker David Akers took to Twitter on Monday, asking people to stop with the harsh remarks directed toward his teammate, saying "ppl need to get a grip! Leave Kyle alone!" Akers also reminded everybody that the NFC West champion 49ers win and lose together, so there wouldn't be any finger-pointing in the locker room.
"I'm irritated with the way people are treating him, absolutely," said Akers, who drew Philadelphia Eagles fans' ire last year with two missed field-goal attempts during a playoff loss. "I think it's ridiculous. You know, get a grip on what life's about. He went out and he put his soul out there. That's what he does. He was not trying to do anything other than make an incredible play for this team. ...
"Mistakes happen. We all make mistakes. But when you're out there truly battling to do the best you can, my hat goes off to him, to anybody that does that."
Many of the 49ers spent the time after the game and into Monday thinking about the missed chances -- and not just by Williams.
Williams said he didn't have any regrets about trying to make a return on the overtime play, with a berth in Super Bowl XLVI on the line.
"When you're out there, you want to make a play," Williams told Comcast SportsNet Bay Area. "You want to make a play for your team. We weren't exactly moving forward. It was one of those things that we needed something to spark us and ... I wouldn't go back and change it."
The Associated Press contributed to this report.