Bonnie Delgado Black, an Arlington mother who had been going through a contentious divorce and custody battle, penned a hopeful note police would find in her kitchen. “I am determined to have a different ending to my story,” she wrote.

Instead, prosecutors say her estranged husband wrote a brutal ending for her, stabbing her to death in the home she shared with their two young children. They argue that David Black, whose murder trial began this week, was an abusive husband angry that his wife was on the verge of a favorable divorce settlement.

David Black has maintained his innocence, and in opening arguments Monday, defense attorney Joseph King told jurors that arguments during a divorce “don’t point to murder.”

King emphasized the lack of physical evidence linking David Black to the stabbing and said Black was optimistic that he’d be able to make his case regarding the divorce settlement.

“There’s nothing at all that links Mr. Black to his wife’s death,” King said.

Bonnie Black’s body was found the morning of April 17, 2015, after her then 5-year-old daughter and 3-year-old son were spotted wandering outside. Black, 42, had been stabbed 14 times in the throat and once in the heart, prosecutors said. The murder trial is expected to last about three weeks.

The victim’s mother, Bettyann Armstrong, testified Tuesday, describing her daughter’s marriage as difficult. She said when Bonnie Black filed for divorce in April 2014, she brought the children to Pennsylvania to stay in a “safe hotel” near both her parents.

Bonnie Black later testified in the divorce case that she fled because her husband had “looked at me with his menacing look and he said, ‘If you ever leave, I will take the children and you will never see them again.’ ”

She said in the same hearing that “emotional and verbal abuse is constant” in the marriage and that she and her husband had been sleeping in separate rooms for over six months.

David Black denied any abuse, testifying in the divorce case that his wife’s behavior was “increasingly impossible . . . hot or cold” and that she was upset at him for financial problems with his house-flipping business.

Once she won preliminary custody, Bonnie Black went back to Arlington. But Armstrong testified that her daughter’s husband would repeatedly violate the court’s orders by coming to see the kids outside his visitation times.

“He was antagonizing my daughter . . . over and over again,” she said.

Armstrong testified that on one occasion when she was watching the children, David Black came over and began pounding on the door, demanding to be let in. Bonnie Black, a psychologist who did contract work for the FBI, regularly traveled for work and left her children with her mother.

“I was getting scared he would knock the door down,” Armstrong said. David Black, she recalled, kept asking her, “ ‘Are you crazy, Grandma? Are you crazy?’ ”

Another time, she said she listened from upstairs as David Black came to the door while her daughter was entering the house with the children. He put his foot in the door and insisted on seeing the kids, Armstrong testified, and would not leave until Bonnie Black threatened to call the police.

On Thanksgiving of that year, Armstrong said, her daughter called “hysterically crying.” Court documents show that Bonnie Black accused her husband of shoving her and stomping on her feet while refusing to let go of their daughter. He wouldn’t leave, she later testified, unless she promised to let him take the children for the weekend. Bonnie Black called the police and soon obtained a protective order against her husband. Officials say David Black was arrested a few weeks later for violating that order.

After the Thanksgiving incident, Armstrong testified, her daughter’s father, Joseph Delgado, went to stay in Arlington and followed his daughter everywhere with a baseball bat.

“He was to be her protector,” Armstrong testified. “Wherever she went, he was there to protect her.”

In February of 2015, however, Delgado went home. He was a 69-year-old man and needed a break, his ex-wife explained.

Two months later, Armstrong said, on April 16, 2015, her daughter called. She wanted to come up to Pennsylvania the next day to relax while waiting for the divorce to be finalized.

A friend, Patricia Fitzgibbon, testified that around that time, Bonnie Black “was concerned if she would wake up in the morning” because of her husband.

But Armstrong testified that her daughter “was happy; it was going to be over. It was going to be safe.”

Bonnie Black was found dead the next day.