What's wrong with that, AOG ? Pretty clear cut case of 'diminished' and an appropriate sentence. Did you want her not jailed at all, then, or were you being uncharacteristically sarcastic? There was an argument for not jailing her.
Or do you want the law changed? Provocation was a defence to murder, reducing it to manslaughter, at common law, and diminished responsibility, which does the same, has been a defence since 1957. They are now combined in a general defence of "loss of control" under the Coroners and Justice Act 2009. So you'd be changing law, in this case, going back over 50 years. It has served us well.