PLYMOUTH, Mass. \u2014 In the months after the birth of her third child, Lindsay Clancy's mental health collapsed. Manic, unable to sleep and stricken with thoughts of harming herself, she sought care from experts in post-pregnancy mood disorders, was put on multiple psychiatric medications, and when nothing worked, checked in to a psychiatric hospital.Nineteen days after she was discharged, she strangled her three children at their Massachusetts home.A jury heard opening statements Monday in Clancy's murder trial, which is expected to feature dueling views about her mental state. Both sides agree she killed her children. They disagree over whether she should be held criminally responsible for their deaths.The first witness was Patrick Clancy, her former husband, who found the children's bodies after returning home on the day of the killings in January 2023. He has said in interviews that he forgives his wife, and will testify for both the prosecution and the defense.He told prosecutors on Monday that a month before the killings, his wife began to describe suicidal and intrusive thoughts of harming the children, but denied having plans to hurt them or herself. He said the situation was "very confusing" because moments later, she would be making the children lunch or playing with them."I never saw Lindsay harm the kids," he told jurors.Despite around four months of psychiatric care, changing medications and new providers, her condition continued to get worse, he said. She became increasingly depressed, struggled to sleep and lost weight.Prosecutors say Clancy strangled her children \u2014 Cora, 5, Dawson, 3, and Callan, 8 months \u2014 after sending her husband out to do some errands. She then used multiple methods to try to end her own life. She remains paralyzed from the waist down after jumping from the home's second-story window.Clancy, seated in a wheelchair, wiped her eyes with a tissue at times as lawyers discussed her children.Defense lawyer Kevin Reddington said Clancy, a former labor and delivery nurse at Massachusetts General Hospital, was suffering from postpartum psychosis. The rare mental illness is linked to the stress, sleep deprivation and hormonal changes that follow childbirth. He argued she had bipolar disorder and that antidepressants prescribed after the birth of her third child worsened her condition."She loved those children right up to the time of their death," he told jurors, saying they would hear from family, frien