(1) In any prosecution under KRS 508.010, 508.020 or 508.030 in which intentionally causing physical injury or serious physical injury is an element of the offense, the defendant may establish in mitigation that he acted under the influence of extreme emotional disturbance, as defined in subsection (1)(a) of KRS 507.020.
(2) An assault committed under the influence of extreme emotional disturbance is:
(a) A Class D felony when it would constitute an assault in the first degree or an assault in the second degree if not committed under the influence of an extreme emotional disturbance; or (b) A Class B misdemeanor when it would constitute an assault in the fourth degree if not committed under the influence of an extreme emotional disturbance.