SAINT-JEROME - Dr. Guy Turcotte, the cardiologist on trial for murdering his young children, said Tuesday that thoughts of suicide began crossing his mind years ago -- as early as 2007.

Turcotte told a jury hearing his murder trial that he'd thought about ending his life after a particularly bad argument with his wife, one of many during a tumultuous 10-year relationship.

Depressed, lying in bed on a sunny afternoon while his children napped, he contemplated attempting suicide.

Two years later, he did. Police found him hiding under a bed, dying. His children, meanwhile, lay dead in their own beds.

The once-prominent cardiologist explained what made him hesitate in 2007.

"I thought of my kids and I didn't want to die," Turcotte told the jury Tuesday, under questioning from his lawyer Pierre Poupart.

Turcotte was on the witness stand for the second day in a row at his high-profile trial, continuing to speak of a difficult marriage wrought with arguments.

Turcotte's testimony is inching towards the night his son Olivier, 5, and daughter Anne-Sophie, 3, were killed inside a rented home in Piedmont, Que., in 2009.

Turcotte is charged with two counts of first-degree murder in their 2009 stabbing deaths -- less than a month after the couple split.

He has admitted to causing the deaths of the two children but has denied murderous intent or premeditation.

The defence says the case revolves around Turcotte's state of mind at the time of the killings.

Six weeks before those killings, Turcotte says he felt anger as he discovered his wife was cheating on him. She was having an affair with Martin Huot, her personal trainer and a man he considered his friend.

But anger turned to loneliness. Turcotte and his wife Isabelle Gaston split up and he left the family home, after one final family vacation in Mexico.

"I hadn't been alone in five years. When I wasn't at work, I was with my kids," a sobbing Turcotte told the jury, describing his first night in a new house.

"I've lost my wife. She cheated on me, I'm all alone."

Turcotte spent Tuesday talking about a lack of communication in his marriage, his defensive attitude to being reproached by his wife and how heated the arguing got.

"It was a vicious cycle all the time," Turcotte said, adding he felt verbally abused in the final month of marriage.

He said the arguing took its toll and he found it hard, but continued to profess his love for his estranged wife and a desperate need to make the marriage work.

It was for that very reason he agreed to go see a so-called "life coach" -- Luc Tanguay -- in 2007 to help him with his self-esteem and guilt issues.

According to Tanguay's testimony, Turcotte eventually told him he killed the children so that they wouldn't have to see him dead after his own suicide.

Tanguay said the accused told him that Olivier pleaded with him to stop stabbing.

On Tuesday, Turcotte said he loved his children despite the hardships and said he forged bonds with both, particularly as they got older.

"Love is unconditional. You can't know that until you have kids," he said.

"My kids gave me love."

His testimony continues Wednesday.