The Witness for the Defense: A Mystery/Detective, Romance Classic By A. E. W. Mason! AAA+++

The "witness for the defense" perjures himself and saves a woman (whose love he had won seven years before and sacrificed for personal ambition) from conviction of the shooting of her husband, a secret and cruel dipsomaniac. He loses track of her for some time but then finds that he must renounce her again, unwillingly this time, as her love has been given to the man who has married her secretly in spit of his realization of the truth long before she confesses it.