Her hospital offered support groups for people who struggle with unforgiveness - the toxic anger and aggravation that comes from holding on to grudges and blame. A former chaplain there wrote a book about it after noticing that many of the patients he saw were burdened by unresolved hurt and guilt.
Sewell, a testicular cancer survivor from West Chester, saw the book the first time he visited Coley. Both of them had been abused by parents.
Sewell, now 72, hadn't even realized he was still angry at his father, but admitted it was hard to pray for him. He read the book and went to the support group meetings. He was able to forgive his father.
"I felt free," he said. "I felt lighter, unobstructed."
His friend's experience after forgiving her parents was similar.
"She said she felt relief in the midst of all her physical pain," Sewell said.
"She lived when she gave up the anger. . . . She lived and she died happy."
Reactions like that have made the unusual support group a popular option at Cancer Treatment Centers of America's (CTCA) hospital in Philadelphia. Michael Barry's book - The Forgiveness Project, the Startling Discovery of How to Overcome Cancer, Find Health, and Achieve Peace - is offered to everyone who arrives.
Despite the subtitle - Barry says he didn't choose the words - the CTCA chaplains who lead the weekly workshops say forgiving is not a cancer treatment. It can, however, make people feel better - sometimes instantly - at a time when stress is sky-high.
Drew Angus, a nurse-turned-chaplain who leads forgiveness groups with Sister Anne McCoy, said a cancer diagnosis is fertile ground for both emotional growth and personal disappointment. With the prospect of death looming, many people want to make amends with estranged relatives and friends. But they may also be disappointed in people they had expected to step up and help. They often blame themselves for getting cancer. Sometimes they are mad at doctors because of missed diagnoses or perceived poor care. Many are angry with God.
All of that makes forgiveness a huge issue for cancer patients, a fact that led Barry, now retired, to address it directly.
"Quite often, our cancer patients are at the tail end of the curve of life," he said. "It's just a time to get their affairs in order."
Barry brushed aside a question about whether patients who have trouble forgiving will feel they are at fault if their cancer progresses.
"The science is very clear about the impact that stress has on your body," he said, noting that high stress has been linked to weaker immune system response.
"If you choose not to manage your emotions, then you are not doing everything you can do . . . to create the best environment . . . for the immune system to fight the cancer," he said.
Loren Toussaint, a psychologist at Luther College who has worked as a consultant for CTCA and has written a forthcoming book on health and forgiveness, says there is evidence that cancer patients who report poor quality of life don't do as well. He thinks emotional well-being deserves more attention.
"Forgiveness, I think, has its largest role to play in helping people to cope with the psychosocial fallout of cancer," he said.
He said there's strong evidence that stress leaves people worn down mentally and physically. Being angry at others, he said, activates the same kinds of physiological responses as other kinds of stress. One study found that people with a history of forgiveness problems were twice as likely as those with better relationships to have cardiovascular symptoms.
As Angus put it in a recent meeting, "Hate hurts health." Grudges and resentment "take really vital energy."
Studies that have tried to measure the physical impact of forgiveness have found that it slows respiration and heart rate and encourages better metabolic functioning, Toussaint said. "Forgiveness can act as a soothing balm," he said.
Figuring out whether it can have any long-term impact on cancer is a very complicated undertaking. "The answer to any question about cancer is obviously, 'We don't know,' " Toussaint said.
Cancer centers today typically offer extensive support programs for patients and families. CTCA highlights its holistic approach in its marketing. Several patients said the emphasis on emotional and physical support was a factor in their decision to travel long distances to the Philadelphia center.
CTCA patients who are concerned about forgiveness can go to the meetings or get individual help. They are encouraged to write about their feelings in a way that may help them develop empathy for their transgressors or themselves.
Barry said one of the biggest barriers to change was getting people to see how damaging prolonged anger can be. "The greatest challenge with forgiveness," he said, "is finding the motivation to forgive."
At the meetings, Angus and McCoy start by talking generally about unforgiveness and steps others have taken to achieve a different attitude. At one meeting, Angus talked about one of Barry's patients, a woman who let go of her anger against her husband's kidnappers by imagining the criminals as helpless babies - and imagining herself cradling them.
Forgiveness, they emphasized, is a choice.
"When we hold on to anger and bitterness, who does it hurt?" McCoy asked at a recent meeting. "Ourselves."
The word lightness comes up repeatedly as cancer patients talk about forgiving. Few burdens are heavier than a life-threatening illness, but ruminative anger is also a corrosive force.
At one meeting, Donna Hostetler of Forest Hill, Md., talked about forgiving her physically abusive stepfather. When she was "in my hate," she said later, she stuffed her feelings down and ate until she reached 310 pounds. She is 5-foot-2.
"It is possible to move past that. Otherwise you can get stuck literally in that mire," she said. She now thinks her dysfunctional childhood has helped make her kinder and more compassionate. "It's very freeing. I just feel like I don't have a heavy spirit."
Mary Gordon, an ovarian cancer patient from Washington, said she realized holding grudges only hurt her. "It's not healthy," she said. "It doesn't help with your healing. It's a burden and you release it. . . . You feel more light."
Phyllis Ellis, a breast cancer patient from Bloomfield, N.J., forgave her ex-husband and, to his surprise, asked him to forgive her. "I felt relief," she said. "Instant relief. I'm telling you, instant relief."
She also wanted God to forgive her.
Grudges, she tells other patients, get in the way of good things. "I always tell them, you have to forgive because it holds you up. It blocks your blessing."
Valentina McHan, a stomach cancer patient from New York, is not one to harbor grudges. Nor did she think she had hurt others. But she came to the group recently because she has worried that she did something to bring on her illness. "I was thinking, why cancer? I thought it was only grumpy people or people who blame themselves."
She doesn't think that now, but realized she needed to forgive herself and others. Blaming anybody, she said, is "a pollution."