The real-life Martha from Baby Reindeerhas filed an explosive lawsuit against Netflix, claiming the streaming site defamed her by painting her out as an obsessed stalker — and she wants more than $50 million, RadarOnline.com has learned! After threatening to take legal action, Fiona Harvey pulled the trigger and filed the suit on Thursday. In the documents obtained by TMZ, Harvey denied many of Martha’s actions in the limited series, especially continuously hounding the main character played by Richard Gadd. Never miss a story — sign up for the RadarOnline.com newsletter to get your daily dose…