Krista Schofield, 41, is believed to have self-medicated with the drug to cope with pain after falling off a treadmill days earlier.
Her body was found by husband Matthew last October who was taking the drug to cope with his bile duct cancer.
He was too ill to attend the inquest but said that he discovered his wife face down with blue lips in their bed.
In his statement to court, Mr Schofield said: ‘Since Krista’s death it has been a living nightmare.
Krista’s death has completely crumbled the family’s foundations and I don’t know how I’m going to cope. ‘She was a fit, healthy and happy person.
The inquest heard that Krista, who ran a street kitchen for homeless people in Bolton, had previously suffered from anxiety but there was nothing to suggest she wanted to take her own life. Mrs Schofield is said to have had ‘a very strong relationship’ with her husband and two sons and ran an eBay business with her mother. She met her husband while working down south and they moved to Bolton to be closer to her family. Recording the death as accidental, coroner John Pollard said: ‘I think what has happened is she has taken some of this medication that is lying around and has probably got this nagging pain and thought it will ease it, and it has built up as more than she can cope with. ‘Yes, she had problems to deal with, but there is nothing to suggest she would have deliberately taken her own life. ‘She had a good relationship with her children. She has a huge family that were supportive of her. ‘I have said it many times – people who are being treated for illnesses like cancer are prescribed morphine because they need more and more. ‘People see that and think ‘I will take some of that’ and do not realise that those of us who are not prescribed it can only take a very small amount.’