Capello was born in a small village of Calabria, Italy. Her family moved to Brunant in 1896 and settled down in Grijzestad. In 1913 (at age 22), she married newly-arrived Italian immigrant Marcello Montesini. They had two sons, Mario (1914-1973) and Amadeo (1917-1965).
Marcello founded the Montesini crime family and soon became a very rich man. Unlike other mob wives, Fabiana took an active role in "the business" and was known to attend meetings and even participate in other things. She would later get the nickname the "mother of crime" since she was known for controlling her two sons (both of who served as bosses) and was always intervening in family affairs. It is believed that in 1929 she ordered the (attempted, but not achieved) killing of communist President Maarten Dolmatoff, after he planned to nationalize industries where she had interests. When her son Amadeo was killed by the Charles Town Mob, she personally extracted her revenge by killing prominent members Garland and Bassett Smalls.
She took a back role by the late 1960s and devoted her time to making calzone and tiramisu, often filled with poison in order to kill family rivals. When Fabiana died in 1985, her funeral was attended by over 200 people, most of them from Brunant's crime families and even several Italian capos and consiglieres who came to pay their respects.
In 1997 the book History of a Mob Wife was written. This is a biography about Capello which was later adapted into a film with the same name. Fabiana's reputation is almost legendary and the popular expression "mob mom" has come to symbolize an overarching mother who is very controlling over her children's affairs.