Gladys was unaware that her friend Claire had been having an affair with her husband for many years. Gladys was a loving mother, and blamed Malcolm for the deaths of both her children.
After she separated from Sir Malcolm, Gladys remained at the Murrays' home in the country. At Mina's funeral, she berated him for his role in Mina's death and flatly rejected his attempt at reconciliation. She declared that she would keep the house in the country and he the house in London. She also refused to divorce him, as she wished to spare herself the inevitable scandal.
Unbeknownst to Gladys, she had become a target in Evelyn Poole's plan to seduce Sir Malcolm. Evelyn constructed a simulacrum of her, and worked her malevolent incantations on it in London, causing Gladys to suffer at the Murray's country estate. Initially she experienced headaches, but these quickly led to hallucinations. She slit her own throat under the illusion that she was being haunted by ghosts of Mina and Peter.