The shared children of disgraced Louisiana mayor Misty Roberts and her ex-husband allegedly suffered abuse at the hands of the ex-leader’s former lover – who later wound up dead, according to court records exclusively reviewed by The Post.  The disturbing docs reveal Roberts’ ex-husband, Duncan Clanton, went as far as filing a civil restraining order to keep the former couple’s two adolescent children away from local pipeliner William Andrew Cronce – a man he claimed had alcoholic, suicidal and