Mr Park, 53, was facing trial over the death of his wife, Carol, 21 years ago but the charges have been dropped due to lack of evidence.
Speaking through his lawyer, the retired schoolteacher said he wanted to rebuild his life.
"I would now like to try to put all this, including the events of 21 years ago, behind me and try to return to my everyday life," he said.
"I was most relieved to hear that the Crown Prosecution Service had discontinued the charge against me. The last four months since my arrest have been traumatic for myself and my family."
But Mrs Park's brother, Ivor Price, said the news had been devastating and the allegations of his sister's numerous extramarital affairs had left him stunned.
"I am disgusted at the way Carol has been portrayed," he said. "She's not someone who is cheap or had a string of lovers. She was a very intelligent and caring woman who picked her friends carefully."
"She did tell me she was having an affair with a man from Middlesbrough but she was seeking comfort with somebody else.
"There were problems with the marriage and she told me how unhappy she was. But she was a decent and loving woman and she went back to be with her children. I want justice for Carol and the killer must be found."
Mrs Park disappeared from the family home in Leece, Barrow in 1977. Her body was found by divers in Coniston Water on 21 August last year.Detectives said the inquiry was still being pursued and made a fresh appeal for information to help track her killer.Reuse content