The 58-year-old has now told of how a charity helped her cope with the trauma - and has urged other survivors to seek the same help.
Morag, from Kelvindale, in the west of Glasgow, was diagnosed with bowel cancer nearly two years ago, after she took part in a screening programme.
The cancer was caught at an early stage - and after medics removed the lump as well as six inches from her bowel she was given the all-clear in late 2012.
But it was not until the retired Strathclyde Fire and Rescue administrator approached Cancer Support Scotland to help her cope she discovered she had a form of post traumatic stress disorder.
Morag described her ordeal as she accepted £500 from Braehead shopping centre's community fund on behalf of the charity.
The money will be used to provide two people who have been diagnosed with the illness with eight one-to-one counselling or complementary therapy sessions, at Cancer Support Scotland's Calman Centre at Gartnavel Hospital.
Morag said that after her diagnosis and before surgery, she decided she would "suck it up and get on with it". But a few months after her operation the shock really hit her.
Morag said: "One day, I just froze and started crying. I was feeling: 'what if? What if I hadn't taken part in the screening? What if I died?'
"I wondered if it was real and had to look down at my scar to believe it happened.
"I was one of the lucky ones. But everything came down on me like a ton of bricks after I was told I didn't have cancer."
A friend then told Morag about the counselling at the Calman Centre.
She said: "The place was so calm, peaceful and they understood what I was experiencing. One of the counsellors told me it was post traumatic stress."
Morag said the cancer shock made her realise she was not as "relaxed and level headed" as she thought and she took part in a talking therapy.
She said: "I was able to come to terms with my cancer and the fears and anxieties. It made such a difference to me and I hope others can do the same."
Her advice came in the run up to bowel cancer awareness month, which starts on April 1.
Cancer Support Scotland offers a range of therapies and counselling sessions.
Its fundraising manager Shona Smith said: "Thanks to the donation from intu Braehead we will provide two people with much-needed support."
Braehead marketing manager Lydia Brown said: "Morag's story shows how important the charity is to people affected by cancer."
Anyone who would like to contact Cancer Support Scotland should visit www.cancersupportscotland.org or call 0800 652 4531/0141 337 8199.