An exercise in catharsis, the long-awaited follow-up to writer/director Kenneth Lonergan’s operatic “Margaret” is a study of the unrelenting nature of grief and the way it haunts, heals, rallies, and returns; the way, ultimately, it colors the minutiae of life. ‘Manchester’ is cathartic in much the same way that writing and directing the film was, according to Matt Damon, meant to be for Lonergan: an act of defiance against the paralysis of grief. Centered around a brittle, awards-worthy turn from Casey Affleck, ‘Manchester’ revels in the ugly details of life — the uncinematic moments — and tells a story of a shattered man learning (barely) to live again after an unbearable tragedy. It’s far from an original tale, but in Lonergan’s perceptive hands, and with the outstanding performances he coaxes from his supporting cast (especially Michelle Williams and Lucas Hedges), ‘Manchester’ transcends its more familiar trappings to become a searingly imperfect film: because perfection has no place in a representation of grief and the tornado mess it wreaks. By turns heartbreaking and hilarious, ‘Manchester’ is utterly human, a delicate film that succeeds in its lack of a pointed, easy epiphany; in its deep love for its characters; and in its pitch-perfect portrayal of the tender, graceless yet charming disorder of life.