Nancy Kissel's testimony came after her attorneys said earlier they planned to show she was suffering from clinical depression and was acting under diminished responsibility when she was provoked by her husband into the attack.
Kissel's lawyer, Edward Fitzgerald, told the nine-member jury that he planned to use testimony from Kissel as well as medical experts to rebut the prosecution's case that the killing was a carefully planned murder that she methodically tried to cover up.
"This is not a case of rational killing by a woman in her right mind," he said.
Nancy Kissel told a jury in Hong Kong's High Court that Robert Kissel's behavior changed after she had the first of the couple's three children in 1994, and he started forcing her to have oral and anal sex while becoming more emotionally distant and absorbed in his work.
"The more involved he got with the investment banking, the more forceful he was with me sexually," a frail and tearful Kissel said.
Prosecutors say Kissel drugged her husband with a sedative-laced milkshake and then bludgeoned him with a metal ornament. Kissel said in the first trial that she killed him in self-defense after he attacked her with a baseball bat and tried to rape her.
The conviction and mandatory life sentence Nancy Kissel was issued in 2005 was overturned last year because prosecutors improperly cross-examined her and the judge allowed hearsay evidence.
In opening statements last month, prosecutor David Perry revisited the gruesome details of Robert Kissel's death in November 2003. Kissel delivered at least five blows to her husband's head while he was lying face down in the bedroom, subdued by a mix of six drugs, Perry said. She then covered the body with a plastic bag and towels and wrapped it in a carpet, then had it moved to storage, he said.
However, Fitzgerald said the circumstances suggest it was a "frenzied and frantic attack" by someone in "an abnormally heightened emotional state." If it had been a cold-blooded murder, she would have used a weapon such as a gun, not the first thing that came to hand, he said.
He also said there was clear evidence of Nancy Kissel's mental state deteriorating from 2000 to 2003.
In testimony about her husband, who was an investment banker at Goldman Sachs and Merrill Lynch, Kissel painted a picture of a man obsessed with work, moving his family from New York to Hong Kong in 1998 at short notice and leaving his wife to fend for herself after they arrived.
He tried to punch her in the face one night in 1999 during an argument about the birth of their third child, which would have coincided with a deal he was working on in South Korea, she alleged.
He also injured her ribs in 2001 when he flipped her over to try to have anal sex with her, she said.
"I learned not to struggle, just to let him do it," she said, speaking in a clear but soft voice that was at times barely audible. Kissel often struggled to fight back tears during her testimony.
The 47-year-old Kissel was helped backed and forth to the witness stand by court officers. She told the court she now weighed 38 kilograms, 16 kilograms lighter than when she entered prison five years ago.
The first trial against Nancy Kissel, a 47-year-old native of Adrian, Michigan, grabbed worldwide attention with juicy details on the breakdown of a wealthy expatriate marriage in this southern Chinese financial hub. It spawned two books and a TV special.
