The former 100 freestyle world champion later remarked that it was "possibly the greatest choke in Olympic history" and broke down in tears in a televised interview.
Taking a long lay-off after Rio, Campbell has elected to skip the ongoing world championships in Budapest where Swede Sarah Sjostrom smashed the Australian's 100 freestyle world record with a 51.71 second lead-off swim during the 4x100 relay on Sunday.
Despite winning relay gold and silver in Rio, Campbell said she felt "let down" by a sport she had worked so hard to dominate.
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“It hurt me deeply in the way that if you are in a relationship with someone. Swimming let me down," she said in comments published by The Australian newspaper.
“It’s strange, because it was 100 percent me (at fault) and I was in control, but I felt like I had given so much of myself to this thing and it had just really let me down and I was feeling really hurt by it."
Campbell added that she was too scared to return to the pool until she had a casual swim at her Brisbane training pool six weeks after the Games.
"I hadn’t been in the water at all, I had no desire to," the 25-year-old said.
“I was bitter and I was angry and I was frustrated and I was scared and I knew I wanted to make changes in my life but I didn’t know how drastic the changes needed to be and I probably needed that first swim to put everything back in perspective and put all of those demons to rest."
Campbell, who won the 100m freestyle world title in Barcelona in 2013, has yet to commit to a full training regime but plans to ramp up her preparations for the home Commonwealth Games at the Gold Coast next year.
She will then have a tilt at a fourth Olympics at Tokyo two years later.
Campbell's younger sister Bronte is defending her 50 and 100m freestyle titles at the world championships in Hungary but has played down her chances after preparations blighted by pain in both shoulders.
That has boosted Sjostrom's hopes of capturing her first 100m freestyle title after finishing runner-up at the last two world championships.
"She (Sjostrom) is an incredible competitor, watching her swim is like poetry in motion," said Cate Campbell.
"If I want to be the best, and ultimately I am a competitive person and I do want to be the best, that will be the standard I have to get to."
(Writing by Ian Ransom; Editing by Peter Rutherford)
