Not just a biker, but the leader of Britain’s only all-female chapter of the Hell’s Angels, a homicidal stalker, and a therapist. Not everything in Heather Stepheson-Snell’s life was quite as it seemed, but one thing was for sure; when she turned up at her ex-boyfriend’s house with a sawn-off shotgun she meant business. Business that she had meticulously planned out on little cue cards at home, written in girly bubble-writing…