Emma Thompson said she was ‘utterly blind’ to her ex-husband Kenneth Branagh’s affair with Helena Bonham.
The 63-year-old actress said: "I was utterly, utterly blind to the fact that he had relationships with other women on set.
"What I learned was how easy it is to be blinded by your own desire to deceive yourself.
"I was half alive. Any sense of being a lovable or worthy person had gone completely,’ she told the New Yorker, also admitting that she felt "humiliated" by the affair.
Thompson wed actor Branagh, 61, in 1989 and ended their marriage in 1995 following his affair with Bonham-Carter, 56.
The actor and The Crown star Bonham Carter are believed to have started their tryst in 1994 when they played each other’s love interests in Mary Shelley’s Frankenstein.
They went on to have a five-year relationship.
Two years before the pair started the affair, Bonham Carter co-starred with Thompson on 1992 film Howards End.
Since the affair, the actresses’ have also worked together on the Harry Potter series, with Thompson playing Professor Trelawney and Bonham Carter in the role of Bellatrix Lestrange.
Thompson previously admitted that she had "forgiven" Bonham-Carter for the betrayal.
In 2013, she said the break-up was "all blood under the bridge", adding: "You can’t hold on to anything like that.
"It’s pointless. I haven’t got the energy for it. Helena and I made our peace years and years ago."’
The Love Actually star told The New Yorker that she got over her devastation with the help of her now husband of 27 years Greg Wise who "picked up the pieces and put them back together".
The pair met while filming Sense and Sensibility in 1995, which later saw her win an Oscar for Best Adapted Screenplay.
They married in 2003 and share two children, daughter Gaia, 22, and son Tindyebwa, a former child soldier from Rwanda who they informally adopted when he was 16.
Branagh married art director, and current wife, Lindsay Brunnock the same year.
Meanwhile, Bonham Carter has two children, Billy and Nell with her ex-partner film director Tim Burton. The pair split after 13 years together.