O'Fallon, Missouri (CNN) -- Nathan Halbach is 22, with a diagnosis of terminal brain cancer. He knows that "horrible stuff" lies ahead.





His mother, Pat Bond, has been taking care of him full time. But when she needed help, she reached out to the Roman Catholic Church.





After all, his father is a priest.





Nathan was born in 1986, during a five-year affair between his mother and Father Henry Willenborg, the Franciscan priest who celebrated Nathan's baptism. In a story first reported in the New York Times, it was revealed that The Franciscan Order drew up an agreement acknowledging the boy's paternity and agreeing to pay child support in exchange for a pledge of confidentiality.





Now her son -- the youngest of four children -- may have just weeks to live. And when the Franciscans balked at paying for his care, she decided she was no longer bound by her pledge of confidentiality.





"I never asked for extraordinary amounts. I asked for the basic needs and care of my son," Bond told CNN's "AC 360."  But she said the church told her, "No, we are not Nathan's biological father, we have no legal obligation to your son."





Willenborg, whose priestly vows require celibacy, has been suspended from his most recent assignment, in northern Wisconsin, as Catholic leaders investigate allegations that he was involved with another woman -- then in high school -- around the same time he was seeing Bond. Willenborg has acknowledged his relationship with Bond, but denies any inappropriate relationship with the other woman while she was a minor, according to his current bishop.





And his order acknowledges its agreement to support his son, telling CNN they have paid about $233,000 to support Nathan over his lifetime. Since the affair has become public, the Franciscan Order has agreed to pick up Nathan's medical bills and the costs for the funeral that now appears likely.





Willenborg refused to speak to CNN. But a statement to his parishioners in Ashland, Wisconsin, in September, said, "My failure to be faithful to my vows has caused me and many others pain and disappointment. I have regretted this for a long time."





And in October, he told The New York Times, "We've been very caring, very supportive, very generous over these 20-something years. It's very tragic what's going on with Nathan."





Bond, then Patricia Halbach, said she and Willenborg began their affair in 1983. At the time, Willenborg was a priest in her hometown of Quincy, Illinois, about 130 miles north of St. Louis, Missouri.





Bond, then a 27-year-old, married mother of three, went to a retreat for women with troubled relationships. Willenborg was the retreat's spiritual director, and she said he was a "terrific" priest -- "incredibly charismatic, very sought-after."





He began to counsel her on a regular basis. After about three months, at the end of one of their sessions, she said he kissed her. Bond said she went home and immediately asked her husband for a separation, and she said she began a romantic relationship with Willenborg.





Bond said she knew he was forbidden to have sex with her. But she said when in love, "You don't think clearly."





"I make stupid decisions in my life," she said. "I am not perfect, far from sainthood, and I loved him."





During their relationship, Bond was a lay leader in the church, and "We were a very good team, a very dynamic team," she said.





But in 1985, she learned she was pregnant. The pregnancy ended with a miscarriage that October. She said in its aftermath, she ended her sexual relationship with Willenborg, only to resume it the following spring. It was during that period that Nathan was conceived, she said.





Nathan was born in December 1986. Willenborg had to disclose the affair and Bond's pregnancy to his superiors. A deal was negotiated by Father
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