"I thought everyone knew me and I didn't think that one little adjective was going to define me," DeGeneres, 56, exclusively tells PEOPLE in the latest issue. "I didn't have perspective for a while."
But these days, with a hugely successful daily talk show, best-selling books and an upcoming gig as the host of the 86th Annual Academy Awards on March 2, that painful rough patch is a distant, if surreal, memory.
"Now I look at it as a movie that I saw that someone went through," she says, "and I only experience the amazing life that I have right now."
One big reason for DeGeneres' gratitude: her thriving marriage to actress Portia de Rossi, whom she wed in 2008. "I love her so much it kills me," says DeGeneres.
Despite recent tabloid reports of strain in the relationship, DeGeneres and de Rossi are as happy as ever – and even currently remodeling a new home together.
"The tabloids had a photo of Portia not wearing her wedding ring. She goes, 'I didn't wear it because when I ride horses and I'm holding the reins, it gives me a blister!' " says DeGeneres, baffled at the rumors.
"The truth is, and this is corny, I fall more in love with Portia all the time. I really do. She surprises me all the time," she says. "It's what anyone experiences when you find that person that gets you, wants to take care of you, wants the best for you. We're really lucky because we know how rare it is."
It's in part because everything is going so smoothly in her life that DeGeneres accepted the challenge of hosting this year's Oscars.
"I thought why not challenge myself? I'm comfortable right now and it's never good to be comfortable as a performer," she says. "Hosting the Oscars is pretty much the scariest thing you can do. To me, this is right up there with bungee jumping!"
For more from DeGeneres's revealing interview, told in her own words, pick up the latest issue of PEOPLE, on newsstands Friday