Plus, the former partner of the late model and actress opens up to ET about what it's like raising their 11-year-old daughter, Dannielynn, on his own.
Larry Birkhead is sharing some of Anna Nicole Smith's most intimate secrets.
In an exclusive sit-down interview at his home in Kentucky with ET's Kevin Frazier, the 44-year-old shares memories from his relationship with the late model and actress, what it's like raising their 11-year-old daughter, Dannielynn, on his own and why he thinks people are still so fascinated with his former partner.
Frazier kicks off the interview by explaining to Birkhead that he first met him in Los Angeles the night of Smith's infamous slurred speech onstage at the 2004 American Music Awards.
"As bad as that seemed and people were making fun of her, behind the scenes, her phone was ringing off the hook," Birkhead recalls. "People were dropping off scripts, people were wanting interviews and I mean, unfortunately, that's the way it goes, people were talking about her."
While Smith was no stranger to making headlines in Hollywood, Birkhead says she was able to keep a few secrets to herself. He reveals that she was hiding something big in 2006 during her Supreme Court victory regarding her late husband J. Howard Marshall's inheritance.
"She went up [to court] and she wore this big, black trench coat and she got a new black dress," he remembers. "And no one knew she was pregnant [with Dannielynn]. She was laughing inside and thinking -- we were laughing about it saying, 'No one knows.'"
Although Birkhead claims Smith "100%" knew he was the father of Dannielynn, Smith named her attorney and former partner, Howard K. Stern, the father on her daughter's birth certificate.
But following Smith's death in February 2007, Birkhead had a victory of his own when he won the paternity battle against Stern and a few other men after taking a DNA test and proving to the court that he was, indeed, Dannielynn's father.
"One of the things that no one has ever seen before is my actual DNA test that I got when I was holding it up outside the courtroom," Birkhead says. "The judge said I couldn't show anybody at the time, I remember that moment well, so I had it rolled up. 'Yup, it says you are 99.99999999 percent.'"
Birkhead tells ET that Smith also kept secrets in her private journal.
"This is Anna's diary," he shares. "And her planner she was keeping, she was going to get started with her movies she was doing -- The Naked Gun, and she was doing Playboy."
"In this calendar of November '93, she talks about [how] she's doing Entertainment Tonight and it's going to air in November of '93," he adds.
Another thing Smith wrote about in her diary was her desire to have a baby girl:
"I want more children and I want a girl I can dress up … and I don't think I'll ever get married cuz men are pigs."
Birkhead chuckled, telling ET, "There's where she met me, in my defense!"
Of course, Smith's dreams of having a baby girl came true when she welcomed Dannielynn into the world on Sept. 7, 2006. When asked what he thinks Smith would say if she were still around today to see him and Dannielynn together, he said she would "be happy."
"I think [Anna and Dannielynn are] similar in a lot of ways," Birkhead reveals. "A lot of times, I make decisions and think about what Anna would think, or what she would think I did that for."
"I just started trying to fly on my own and say, 'You got to make decisions here,'" he continues. "Although you might hear the voice in your head… just do the best you can, and I think that has been a pretty good formula."
Today, 10 years and seven months after her tragic death, people still seem to be fascinated by Smith.
"I think to some people, she gave them hope," Birkhead says. "That whether it was their dreams of pursuing acting or modeling or just the rags-to-riches story, that people fall in."
"Everybody likes a tragedy and mystery," he adds. "I had somebody come up to me and say, ‘I'm a movie producer and I sit around with a team of people all day long and we couldn't come up with the stuff that you went through. It is just crazy.'"
To hear more highlights from our exclusive chat with Birkhead, watch the video below, and tune into Entertainment Tonight to watch the full interview.