A Dartford GP was "racked with guilt and wanted to die" when he handed his patient a knife and asked her to kill him, a tribunal heard.
Ashamed Dr Andrew Doyle also exchanged sexually explicit texts with the woman and even got her to read his self-penned erotic novels while carrying on the ''improper emotional relationship".
The medic gave her lifts to visit her mother, leant her cash to pay bills and kissed and cuddled her during what he described as "a slippery slope" towards an inappropriate doctor and patient relationship.
Dr Doyle, a partner at the Orchard Practice in Tower Road, told a disciplinary panel in Manchester on yesterday: "I want to apologise to lots of people.
"The first would be my family, then Patient A. The second is no longer available to me."
The Medical Practitioners Tribunal Service has heard the mother-of-three died last year after losing her battle with breast cancer.
Dr Doyle first began treating her in 2005 when she came to him with mental health problems and a history of troubled relationships.
He described a gradual blurring of professional boundaries and said she would "manipulate" him into prescribing drugs, making excuses about losing her medication.
Dr Doyle, who has been suspended since October 2011, told the panel they bonded over a "mutual self-loathing".
He added: "I gradually became involved with Patient A and got out of my depth.
"I lost clinical perspective and made a series of terrible mistakes, which I regret. I feel deep shame."
The doctor admits much of his behaviour towards the woman was sexually motivated, but denied handing the woman a knife and asking her to kill him amounted to such.
He said they had become sexually intimate, adding: "I was racked with guilt and I wanted to die."
The medic admitted sharing his "violent and sexually explicit" erotic novels with the patient but denies overprescribing her the painkiller pentazocine.
But Dr Doyle does admit prescribing the patient excessive quantities of the sleeping pill zopiclone and the strong painkiller codeine.
If the panel, chaired by Dr Surendra Kumar, find against the medic he could face conditions on working, a period of suspension up to one year or being struck off the medical register.
The hearing is listed to continue until March 11.