I Stole the Protagonist’s Woman in a Xianxia Story

He became a disposable villain in a xianxia tale—an extra destined to lose to the protagonist, who had obtained an early fortuitous encounter, and live the rest of his life with an arm cut off. All he wanted was to avoid that miserable fate, but somehow, he ended up winning. Worse, he even stole what belonged to the protagonist, and with a future immortal now certain to torment every one of his futures and reincarnations, he has only one choice: become an immortal himself.