Brenda Young, 65, was diagnosed with invasive cancer of the right breast after a routine scan and a following biopsy, at Barnsley Hospital in February last year.
A couple of weeks later Ms Young, from Hoylandswaine in Barnsley, underwent a mastectomy.
But medical analysis of the removed breast tissue by a regional expert found Ms Young had not had cancer.
And eight days after her surgery, on March 5, Ms Young was told her diagnosis was incorrect.
Ms Young said: "I was told about the fact that I didn’t have cancer around the time that the first lockdown started and therefore had to cope with my horror and anguish alone, without having free access to family and friends and other networks to support me.
"This was incredibly difficult."
Due to the Covid-19 pandemic the NHS were placed under unprecedented pressure to help fight against the new disease, which has led to a disruption to surgery waiting times.
Ms Young said she has had to live with one breast for roughly nine months due to delayed reconstructive surgery.
The hospice nurse said it had been a 'struggle' as she worked through the pandemic while coping with her injury.
She said: "Sadly, the pandemic meant that my reconstructive surgery was delayed until the end of 2020. During this time, I had to live with one breast which made me feel extremely uncomfortable and self-conscious.
“I felt frustrated that I had undergone removal of my breast for a cancer that I didn’t have, but then had to wait so long for reconstruction. As a key worker I had to return to work before my reconstruction.
"During this time, I tried to disguise my injury and the impact it was having on me to those I was looking after."
After instructing Irwin Mitchell solicitors to investigate her treatment, Ms Young said she has now received an apology from Barnsley Hospital NHS Trust - though legal action is ongoing.
Irwin Mitchell said a serious incident report by the trust found doctors did not seek a second opinion when analysing test results before her diagnosis.
A spokesperson from Barnsley Hospital said it had offered an apology to Ms Young and that as Ms Young’s case was an ongoing legal matter under investigation, it would not be appropriate to comment further.
The spokeswoman added: “The Trust has co-operated fully into the investigation and the findings of the report were shared with Ms Young.
"The hospital is always available to discuss any on-going concerns she may have.”
Ms Young added: “I know nothing can make up for what has happened but by speaking out I just hope that I can try and help prevent what happened to me happening to others.”
Rebecca Hall, the Irwin Mitchell lawyer representing Ms Young, said: "The first-hand account we’ve heard from Brenda is truly shocking.
"Understandably what happened to Brenda has not only had a physical effect but also a psychological impact on her."
Ms Hall added a number of patients have experienced "significant issues" with cancer services especially.
She said: "While Covid-19 has had a huge impact on the healthcare system it’s vital that people continue to participate in cancer screening programmes.
"One of the most significant issues facing the system has been around cancer services, with well-documented issues around patients waiting longer for treatments.
"Some patients who have been impacted during recent months will understandably have a number of concerns about their care. It’s crucial that they now receive the help and support they require."