Scott Mitchell, her husband of 20 years, said he acted on the advice of his neurologist but the decision had always been extremely painful.
He said the 82-year-old actress left the couple’s property in mid-July and moved to a retirement home in London.
He told The Sun, “I feel like I’m on an emotional roller coaster. I walk around, trying to keep busy, then burst into tears. It looks like mourning.
“It has always been my biggest fear that one day I would have to take her somewhere and she would be like, ‘Why would he do this to me?’
“This fear has become a reality. This is something I never wanted. ”
Speaking of the day he left Dame Barbara at home, Mr. Mitchell said, “I will never forget the feeling of emptiness. I felt sick in the pit of my stomach that I had left. I still feel like this.
“By the time I got home and went to bed, I was feeling hopelessly sad. It has been 27 years since we first met and we have spent a lot of that time in each other’s company. I have the impression that another chapter has passed.
He decorated his bedroom to make it as welcoming as possible, putting family photos in it as well as a photograph of the actress receiving her Queen’s Lady.
Mr Mitchell, 57, said in June that his wife need full-time care at some point, describing it as something he had “always feared”.
He said at the time that she often didn’t recognize their home and had recently had difficulty walking, prompting her to use a wheelchair.
This week he said: “She still seems unstable and, in her moments of lucidity, I can see that she has realized that it is not temporary. She still thinks and says I let her down. Of course, it’s a painful thing to hear, but I know it’s not the Barbara I know speaking.
“And, let’s be honest, who else is she going to blame?” I just have to smile at her and tell her that I love her and everything I do is for her best well being. I am no different from the millions of other people who would have gone through this. ”
Dame Barbara was diagnosed with Alzheimer’s disease in 2014 and Mr. Mitchell revealed the news publicly four years later.
Recalling the moment the couple were informed of the diagnosis, he said: “She started to cry, then held her hand, reached out to me and said ‘I’m sorry’.
“I squeezed his hand back and said, ‘Don’t worry, you’ll be fine.’
Mr Mitchell said he first noticed symptoms of Alzheimer’s disease in 2009 when Dame Barbara began to have trouble learning her lines.
In 2016, the forgetfulness and confusion were worse, and it was agreed that she would step down from her acting role as pub owner Peggy Mitchell at EastEnders.
In September of last year, the couple delivered a letter to Downing Street signed by 100,000 people, asking for better support for people with Alzheimer’s disease.
The letter said dementia care across the country was “difficult and sometimes even impossible to access.”
Dame Barbara made her stage debut at the age of 13, but it was her work in the Carry On films in the 60s and 70s that made her a star.
She received an MBE in the Millennium New Year honors.
Away from her acting roles, Dame Barbara is arguably most famous for her support for the Royal British Legion’s Poppy Appeal.
She has now retired from charity work and acting.