In 1965, Bisceglia met her future husband, Dan Broderick (1944–1989), at the University of Notre Dame in South Bend, Indiana. Broderick was born in Pittsburgh, Pennsylvania; he was the eldest son of a large Catholic family akin to the Bisceglias, and both his parents were descendants of Irish immigrants. The couple married on April 12, 1969, at the Immaculate Conception Church in Tuckahoe. Betty returned from her honeymoon pregnant with her first child, daughter Kim (b. 1970). She gave birth to four more children: daughter Lee, (b. 1971) two sons named Daniel (b. 1976) and Rhett, (b. 1979) and an unnamed boy, who died two days after birth.
After Kim's birth, Dan completed his medical degree at Cornell University. He then announced his intention to combine his medical expertise with a law degree. He enrolled at Harvard Law School. Betty became the main provider for the family, working to support the family while Dan attended law school with the help of a student loan. Dan was an attractive prospect for many firms that had backgrounds in medicine and law. He was quickly hired by a law firm in San Diego, California, and moved his family to the nearby community of Coral Reef. He began to specialize in medical malpractice cases. At this point, Betty functioned as a stay-at-home mom; she focused on caring for the children and being a housewife. In the fall of 1983, Dan hired 21-year-old Linda Kolkena (1961–1989) to be his legal assistant; she was a former Delta Airlines flight attendant of Dutch descent who came from a large close-knit family.
As early as October 1983, Betty suspected that Dan was having an affair with Linda, and she accused her husband of cheating on her. He denied engaging in extra-marital sexual relations with Linda Kolkena, telling Betty that she was ""crazy."" Eventually, the marriage broke down, and against Betty's wishes, Dan Broderick moved out in February 1985. He bought a house of his own, and eventually took custody of their children after Betty dumped the children on Dan's doorstep one by one. Dan confessed to Betty that she had been right all along: he had been having an affair with Linda since January 1983. Afterwards, a long, drawn-out, and very hostile divorce proceeded. Broderick vs. Broderick became one of the more famous divorce cases in the United States, not least because of certain legal issues involving women who had worked while putting their husbands through graduate and professional school.
The long, drawn-out Broderick divorce was finalized in 1989, four years after Dan filed the petition. Betty's behavior became increasingly more violent and irrational. He retained custody of the children, though this was for non-financial reasons; he had been looking after them for some time. During this time, Betty left hundreds of obscene and profanity-laden messages on Dan's answering machine. She ignored countless restraining orders that forbade her from setting foot on Dan's property.
