Gary Rentz described her plans to leave Brad.
"She said 'Dad I'm through. I've got to get out,'" Rentz told jurors.
Brad Cooper is accused of killing Nancy in 2008. Her body was discovered next to a storm water retention pond in an unfinished Cary subdivision July 14 - two days after she was reported missing. An autopsy showed she was strangled. Prosecutors say Brad killed Nancy because he was angry she planned to divorce him and move with their two daughters to Canada.
On the witness stand Thursday, Rentz testified about the steady disintegration of the Cooper marriage. He spoke of the couple's disagreements over money. Other witnesses have said that Brad took away Nancy's access to credit cards and bank accounts and gave her cash every week instead.
Rentz read from an email from Nancy titled "I need your help."
"Brad has gone a little crazy," Rentz quoted. "He has had the water cut off and has taken me off all the bank accounts."
A voicemail was played that Nancy left Rentz following a family trip to Hilton Head in June 2008 shortly before her death.
Nancy and her daughters had gone to Hilton Head to be with her parents, and when she returned, she was furious because Brad had done nothing to clean the house while she was gone.
"The place is so dirty," Nancy tells her father in the voicemail message.
She said there were ants everywhere and she had to call an exterminator.
Rentz also spoke of what happened July 12, 2008 when he learned Nancy was missing. Rentz testified that he told his wife that "this is not going to have a happy ending."
Rentz said he based that opinion on what he knew of the marriage and his conversations with his daughter in the preceding months.
During Rentz's testimony, parts of a deposition Brad Cooper gave in 2008 was played for the jury. The testimony was for a case in which Nancy's family sought custody of the Cooper's daughters - who now live with them in Canada.
Under oath, Cooper was asked about an affair he had with a friend of Nancy's called Heather Metour. Cooper said he had sex with Metour in the closet of the master bedroom of his house and that his oldest daughter and Metour's children were in the house at the time. Cooper said the episode lasted approximately 15 minutes.
Cooper also recounted another incident during which Metour performed oral sex on him in his home. He could not recall if anyone else was in the house at the time. Cooper denied having sexual relationships with anyone else.
Also in the deposition, Cooper said he had been seeing a psychologist after Nancy's death to help him deal with the loss.
The playing of the deposition tape hit a snag when a portion that was not supposed to be played for the jury was inadvertently shown to them.
Cooper's defense lawyers immediately objected - saying the material about contacting a former girlfriend is highly prejudicial.
"They can't unhear it," said attorney Howard Kurtz and accused prosecutors of doing it intentionally.
Prosecutors immediately denied that.
Judge Paul Gessner told jurors that Cooper was contacting the woman to try and get the number for a lawyer.
While prosecutors maintain the murder happened after the Coopers returned from a neighborhood party July 11, Cooper told detectives his wife went out for a run the morning of July 12 and never returned. Coopers lawyers say he is innocent and have characterized the investigation by the Cary Police Department at inept. They say detectives focused on Cooper from the beginning of their investigation and never looked at other suspects.