the.com/hair shirt

means An uncomfortable duty or guilt you deliberately keep enduring, long after you could have set it down.

from Literally a shirt woven from coarse animal hair (often goat or horsehair), worn next to the skin by medieval monks and penitents to cause constant itching and discomfort as an act of religious self-mortification — physical suffering offered up to atone for sin or discipline the flesh. The practice is ancient, with roots in early Christian and even earlier ascetic traditions. By the 19th century the phrase had shed its literal garment and come to describe any self-imposed, ostentatious misery — guilt worn like clothing, chafing on purpose.