Portia de Rossi Feared Coming Out About Ellen DeGeneres Relationship: 'That's It, I've Killed My Grandma'

Portia de Rossi didn't formally come out — except to her grandmother.

In a conversation with wife Ellen DeGeneres on The Ellen DeGeneres Show Tuesday, the 49-year-old actress recounted when she told her grandma that she was dating the famous comedian, now 64.

DeGeneres began the conversation, telling her wife, "Since we've been together, many things have changed. You came out by just being with me — that was your outing. But your story about telling your grandmother that you were with me is a beautiful story that I would love you to share."

De Rossi recapped her relationship with her grandmother, including her grandma's love of DeGeneres's eponymous show — before the star made a historic decision.

"She was so special to me and she was a huge fan of Ellen. She loved the sitcom — in Australia. Loved the sitcom, wouldn't miss an episode … until the episode where she came out," de Rossi said.

"Now, I know I'm gay at this point and I love my gran, and the minute that Ellen came out she refused to watch the show," she said. "In fact, if a commercial for her show came on, she would change the channel and say 'That disgusting woman.'"

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

talk show host Ellen DeGeneres and Portia de Rossi are seen during a taping of "The Ellen DeGeneres Show" at the Warner Bros. lot in Burbank, Calif.
talk show host Ellen DeGeneres and Portia de Rossi are seen during a taping of "The Ellen DeGeneres Show" at the Warner Bros. lot in Burbank, Calif.

Michael Rozman/Warner Bros.

Years later, once de Rossi had begun her own acting career in Los Angeles, she returned to Australia to see her family.

Her grandmother asked if de Rossi was dating anyone — and the actress decided to reveal her sexuality, specifically her relationship with DeGeneres, despite her knowledge that the 99-year-old had soured on DeGeneres after she came out.

"At this point, my mom was supposed to have told Gran that I was with Ellen. And she knew that we lived together. And I said 'Gran, I'm with Ellen.' And she said 'Ellen? Who's Ellen?'"

RELATED: Ellen DeGeneres' Iconic 'Coming-Out' Episode — Why It Was So Groundbreaking

De Rossi continued, "I said, 'Yeah, you knew that I lived with Ellen,' and she said, 'Yes, and all this time I was worried that that lesbian was hitting on my granddaughter.'"

For a moment, de Rossi was unsure if her relationship with her grandmother would continue. "So she literally put her head in her hands for 20 seconds, 30 seconds, silent, and I thought 'That's it. I've killed my grandma,' de Rossi said. "I really thought that I did. And she just looked at me, and she goes, 'Well, I love you just the same.'"

The couple talked about the beauty of the moment and de Rossi's grandmother's decision to support her granddaughter.

talk show host Ellen DeGeneres and Portia de Rossi are seen during a taping of "The Ellen DeGeneres Show" at the Warner Bros. lot in Burbank, Calif.
talk show host Ellen DeGeneres and Portia de Rossi are seen during a taping of "The Ellen DeGeneres Show" at the Warner Bros. lot in Burbank, Calif.

Michael Rozman/Warner Bros.

RELATED: Ellen DeGeneres and Portia de Rossi Celebrate 13th Wedding Anniversary: 'I'm the Luckiest Girl in the World'

After the couple married in 2008, the year that California made same-sex marriage legal, DeGeneres noted that her wife's grandmother "died at 103 with our wedding picture next to her bed."