In the 2003 film, Emma realises her husband is having an affair after discovering the jewellery he has bought for another woman.
Now the 58-year-old actress has revealed she nailed the famous scene because she had her heart “very badly broken” by her first husband Kenneth Branagh.
The couple married in 1989 after falling in love on the set of the BBC drama ‘Fortunes Of War’ but filed for divorce in 1995 after the director and actor was linked to his ‘Frankenstein’ co-star Helena Bonham Carter.
“That scene where my character is standing by the bed crying is so well known because it’s something everyone’s been through’, Emma told the audience at a fundraiser for the Tricycle Theatre in North West London
“I had my heart very badly broken by Ken. So I knew what it was like to find the necklace that wasn’t meant for me.
“Well it wasn’t exactly that, but we’ve all been through it.”
In 2013, Emma revealed that she had “made peace” with Helena and described her as a “wonderful woman” in an interview with The Sunday Times.
She said: “I’ve had so much bloody practice at crying in a bedroom, then having to go out and be cheerful, gathering up the pieces of my heart and putting them in a drawer.
“That is... all blood under the bridge. You can’t hold on to anything like that. I just think... pfft.
“It’s pointless. I haven’t got the energy for it.. Helena and I made our peace years and years ago... she’s a wonderful woman.”
Watch the scene from ‘Love Actually’ below...