Complex sentence: After her death, it was believed she had been poisoned by a lady attendant from Germany, Ourse de la Viefville, a close confidante who had been dismissed to Aire just before Michelle's death.
Split into simpler sentences: After her death, it was believed her death had been brought on by poisoning by a lady attendant from Germany, Ourse de la Viefville. This lady had been a close confidante of the Princess, however had been dismissed to Aire just before Michelle's death.