In a case that has cast a long, unshakable shadow over Long Island for more than a decade, Rex Heuermann has finally admitted to the unthinkable. On Wednesday, the 62-year-old architect stood in a Suffolk County courtroom and pleaded guilty to murdering seven women, while also confessing to an eighth killing that had not previously been charged. It was a moment that many families had been waiting years to hear, but one that brought little sense of relief.