The majority of Celeste Wright's story in season two revolves around the increasing animosity between her and her mother-in-law, Mary Louise. The latter is dead-set on finding out the truth about what happened to her son, Perry, who she doesn't believe tripped and fell to his death the night of the school fundraiser the year before. Mary Louise invades Celeste's space and creates plenty of tension for the grieving widow, and eventually files a suit against Celeste in an attempt to wrestle away custody of her young twins, Max and Josh.
The season two finale gives us closure on Celeste and Mary Louise's battle in court. Celeste, a former attorney, is granted permission by the judge to question her mother-in-law herself, and proceeds to rip apart Mary Louise's prejudices and judgments against her parenting style. One of the ways she does this is by bringing up the death of Perry's little brother, Raymond, who died decades earlier in a car crash while Mary Louise was driving. Celeste says Perry told her that his mother cruelly blamed Raymond's death on him for years.
Celeste also decides to play footage of Perry physically abusing her in court, which one of her boys recorded. Finally, people believe that Celeste was telling the truth about the abuse, and she's granted custody of her kids and the case is dismissed. Mary Louise, clearly shaken, is sent packing, hopefully never to be heard from again.