Guy Turcotte murder trial hears from kids' mother

Guy Turcotte, right, and his lawyer, Pierre Poupart arrive at the courthouse Monday, Sept. 28, 2015 in Saint-Jerome, Que. Turcotte is being retried for the murder of his two children.(THE CANADIAN PRESS / Ryan Remiorz)

SAINT-JEROME, Que. -- The day his children were killed, an ex-Quebec doctor who stands accused in their stabbing deaths declared war on their mother, she told the court on Monday.

Isabelle Gaston's emotion-packed testimony took centre stage at the trial of her ex-husband, Guy Turcotte, who is facing two counts of first-degree murder in the 2009 slayings of Olivier, 5, and Anne-Sophie, 3.

Turcotte, 43, has pleaded not guilty to the charges but admitted last week, through a statement of agreed facts filed by the lawyers, to causing the deaths.

The Crown has said the children were stabbed 46 times.

Gaston kept her back to the accused and her focus on the jury as she described, while responding to prosecutor Rene Verret's questions, how their rocky relationship came to an end in January 2009.

In the weeks that followed, Gaston said, she decided to have the locks on the family home changed after several unannounced visits by Turcotte, including one where he reportedly punched her new lover.

On Feb. 20, 2009, Gaston and Turcotte had a telephone conversation, with Gaston testifying Monday he was livid after learning about the lock change.

"You had no right, it was my house," Gaston quoted Turcotte as yelling at her over the phone. "If you want a war, you'll have it."

She pulled over while driving to a ski weekend near Quebec City, trying to call Turcotte back several times without success.

By the next morning, the children were discovered dead.

Earlier, Gaston said the couple met in 1999 and were married for six years before splitting in January 2009 -- less than a month before the young children were found stabbed to death in a home Turcotte had rented following the split.

Gaston said there were "ups and downs" throughout the marriage and, that by 2008, she had fallen in love with her personal trainer, Martin Huot, who was also an acquaintance of Turcotte's.

Gaston testified she was on vacation with Turcotte and their children in Mexico in January 2009 when an email from Huot informed her that his ex-girlfriend had outed their infidelity to Turcotte.

"I regret that my relationship wasn't over," she told the jury, suggesting a wish she'd formally ended her marriage before taking up with Huot.

She said Turcotte was never clear about how he felt about the separation -- sometimes expressing optimism and relief, other times anger and a refusal to accept Huot's growing presence in his children's lives.

Gaston also noted she twice found gay pornography on Turcotte's computer, which caused friction in the relationship. She says she froze when she saw the images and confronted Turcotte, who downplayed it.

She will face more cross-examination on Tuesday from the defence.