Del. Code tit. 11 § 641
The fact that the accused intentionally caused the death of another person under the influence of extreme emotional distress is a mitigating circumstance, reducing the crime of murder in the first degree as defined by § 636 of this title to the crime of manslaughter as defined by § 632 of this title. The fact that the accused acted under the influence of extreme emotional distress must be proved by a preponderance of the evidence. The accused must further prove by a preponderance of the evidence that there is a reasonable explanation or excuse for the existence of the extreme emotional distress. The reasonableness of the explanation or excuse shall be determined from the viewpoint of a reasonable person in the accused's situation under the circumstances as the accused believed them to be. Extreme emotional distress is not reasonably explained or excused when it is caused or occasioned by the accused's own mental disturbance for which the accused was culpably responsible, or by any provocation, event or situation for which the accused was culpably responsible, or when there is no causal relationship between the provocation, event or situation which caused the extreme emotional distress and the victim of the murder. Evidence of voluntary intoxication shall not be admissible for the purpose of showing that the accused was acting under the influence of extreme emotional distress.
11 Del. C. § 641