Hudson sobbed Wednesday during final arguments.
The defense for Balfour, Hudson's former brother-in-law, told jurors that prosecutors failed to prove their case, while prosecutors countered that they had "a tsunami of evidence" linking Balfour to the crime.
Hudson, who attended every day of testimony, bent forward, her head on her knee, and cried as prosecutor Jennifer Bagby described what she called "the execution" of her family members in October 2008. Bagby showed jurors photos of the victims' bloody bodies juxtaposed with pictures of them alive.
"This defendant is the one that made (them) into these images," Bagby said, glancing back at the photos.
Balfour has pleaded not guilty to three counts of first-degree murder. If convicted on all counts, he faces a mandatory life prison term.
In her closing argument, public defender Amy Thompson accused prosecutors of not proving their case.
"I am offended," she added, "that they would ask you to throw your logic away."
Balfour and Julia Hudson were estranged but not yet divorced when the shootings occurred, and prosecution witnesses testified he threatened dozens of times to kill the Hudson family if Julia Hudson refused to reconcile with him.
Prosecutors say Balfour shot Hudson's mother, Darnell Donerson, in the living room of the Hudson family home Oct. 24, 2008, then shot Hudson's brother, Jason, in the head as he lay in bed.
Balfour allegedly then abducted the boy, Julian King, and shot him as he lay behind a front seat of a sports utility vehicle. His body was found in the abandoned vehicle after a three-day search.
During her closing, Bagby laid the murder weapon, a silver and black .45 handgun, on a podium feet in front of the jury, and it clanged as it hit the wood.
She said gunshot residue from it was found on the steering wheel of Balfour's green Chrysler. Bullets taken from the bodies were fired from the same gun, Bagby said.
Prosecutors presented weeks of testimony, starting with Jennifer Hudson. She told jurors about the last time she saw her three family members alive and spoke endearingly about her nephew, Julian King.
The defense called just two witnesses - two detectives who had testified earlier - in a bid to suggest investigators botched the triple-homicide investigation.