Hillary Clinton has spent the last 10 months trying to figure out why she isn't the president of the United States. 

"I am good," Clinton told "Sunday Morning" anchor Jane Pauley. "But that doesn't mean I am complacent or resolved about what happened. It still is very painful. It hurts a lot." Jane Pauley:

As the polls closed, Clinton's supporters gathered in a New York City convention center, expecting to see history being made.  But as the returns came in, the celebratory mood began to fade.

"I just kinda went in the bedroom, laid down on the bed, just thought, 'Okay. I just have to wait this out,'" Clinton said. "But then, midnight, I decided, 'Well-- you know, looks like it's not gonna work.'"

After midnight, she called Donald Trump, the president-elect.  And then she called the White House.

"I felt like I had let everybody down," she said.

Morning came, and the nation was waiting to hear from her.

"I had not drafted a concession speech. I'd been working on a victory speech," she laughed.

And then, on what she thought would be her first day as president-elect, Hillary and Bill Clinton headed to their home in Chappaqua, New York.

"I just felt this enormous letdown, just kind of loss of feeling and direction and sadness," Clinton said. "And, you know, Bill just kept saying, 'Oh, you know, that was a terrific speech,' tryin' to just kinda bolster me a little bit. Off I went, into a frenzy of closet cleaning, and long walks in the woods, playing with my dogs, and, as I write-- yoga, alternate nostril breathing, which I highly recommend, tryin' to calm myself down. And-- you know, my share of Chardonnay. It was a very hard transition. I really struggled. I couldn't feel, I couldn't think. I was just gob-smacked, wiped out."

Weeks passed.  But she couldn't remain in seclusion forever.

"You know, after the first of the year, I had a big decision to make. Was I going to go to the inauguration?" she said.

Defeated candidates don't necessarily attend the inauguration, but Clinton was in a unique position.

"But I'm a former first lady, and former presidents and first ladies show up," she said. "It's part of the demonstration of the continuity of our government. And so there I was, on the platform, you know, feeling like an out-of-body experience. And then his speech, which was a cry from the white nationalist gut."

On January 20, Mr. Trump took the oath of office and delivered his inauguration speech.

"This American carnage stops right here and right now," Mr. Trump said.

Said Clinton of the speech: "What an opportunity to say, 'Okay, I'm proud of my supporters, but I'm the president of all Americans.' That's not what we heard at all."

Clinton had been so sure she'd be the one giving that inaugural speech.

"Well I know a lot about what it takes to move a president.  And I thought I was going to win," she said. 

The Clintons had acquired the house next door, to accommodate White House staff and security during a second Clinton Administration.

At a dining room table in that house, she wrote about "What Happened." 

"I couldn't get the job done, and I'll have to live with that for the rest of my life," Clinton wrote in the memoir.

So:  What did happen?  Hillary Clinton was supposed to make history as the first woman president of the United States.

"I started the campaign knowing that I would have to work extra hard to make women and men feel comfortable with the idea of a woman president," she said. "It doesn't fit into the-- the stereotypes we all carry around in our head.  And a lot of the sexism and the misogyny was in service of these attitudes. Like, you know, 'We really don't want a woman commander in chief.'"

Her opponent -- real estate billionaire and reality TV star, Donald Trump, a political novice who had previously defeated 16 GOP primary challengers.   

"He was quite successful in referencing a nostalgia that would give hope, comfort, settle grievances, for millions of people who were upset about gains that were made by others because—" Clinton said.

"What you're saying is millions of white people," Pauley said.

"Millions of white people, yeah," Clinton replied. "Millions of white people."

And then the Russians.  American intelligence began picking up signals that Moscow was attempting to influence the election in Trump's favor -- both by hacking into Democratic National Committee e-mails and by spreading false information online.

"The forces that were at work in 2016 were unlike anything that I've ever seen or read about. It was a perfect storm," Clinton said.

Read more at CBSNews.com.