More on the Bradford killings, with video
Christine Thompson, 72, was on holiday with her family in Greece when she was told that police believed her daughter Susan Rushworth, 43, was one of three prostitutes killed by the same man.
Despite their anxiety, the family had to wait until the end of their break before returning to the UK because no earlier flights were available from Halkidiki.
Mrs Thompson had been away with her husband Barry and grandson James Rushworth at the time.
It was news she had been dreading for almost a year, since Miss Rushworth, who suffered from epilepsy and had a serious heroin habit, unexpectedly went missing.
She disappeared in June, after leaving her flat in Oak Villas, Manningham.
Mrs Thompson said: "I always thought there might be a glimmer of hope that I would see Susan again alive and well but it was not to be.
"She used to come round regularly and would always knock on the window and I used to think, would she ever do that again?
"I'm just devastated – I feel that my world has collapsed and I don't know how I will cope without her.
"We were enjoying our holiday and had been there for about 10 days when James rang home and found out what had happened.
"We had to go back to our apartment where he told me. He broke into pieces and I started screaming.
"It is a tragedy what happened to Susan. I tried my best to help her and paid 3,000 for her to attend a rehabilitation clinic in Harrogate five or six years ago but the treatment only worked for 10 months before she went back on the heroin again.
"She was my best friend and like a sister to me. She was my world and these last 11 months have just been agony waiting to hear the news we have all feared.
"There was always a glimmer of hope but now we know the truth."
Mrs Thompson's husband Barry has been suffering from dementia for some years and is unaware of what has happened to his daughter.
She said: "He would say to me, 'What are you crying for?' I would say, 'it's our Susan, she is missing' and he would say, 'Is she?' "The saddest part is not being able to share what has happened with my husband – we will be celebrating our golden wedding anniversary next April."
At the time of her disappearance, Miss Rushworth was attempting to change her life. She had not worked the streets of Bradford's red light district for three weeks, was undergoing treatment for her addiction and had started to form a relationship with her grandchildren.
At the time her son James Rushworth appealed to anyone who might have seen his mother saying: "We are a close family and we are not coping very well.
"She has been off heroin for five weeks before she went missing and there's no reason that she would have left. I have got three children and she has only recently started seeing them. She was just getting to know them."
Mrs Thompson, a mother-of-three, of Thornton, Bradford, added: "Susan would do anything for me. She would bring me flowers and little gifts. She knew how she had hurt us – doing the drugs and prostitution and she would say, 'I am sorry about what I have done to you, mum.'
She once sent me a letter three years ago which I have kept. It said: 'Dear Mum and Dad, you are the best mum and dad in the world. No other mum and dad would do what you have done for me. I would die for both of you. I love you so much."'