Yup, the law says if the threat isn't imminent you go to the cops but if it's proven the cops won't help??? I don't think I could vote to convict in such a situation.
Why not? She could have easily left without committing arson and premeditated murder first.
Besides, you are assuming that everything she said was 100% true and nothing was invented, exaggerated or embellished in the aid of her defense. She had a vested interest in lying about the abuse, and he was dead and not able to defend himself or rebut any of her claims. Very convenient for a murderer.
If the genders were reversed and the claims the same, would you be so quick to believe a man who set his wife on fire?