Monjack told PEOPLE he was "ridiculously upset" on Thursday – the day the L.A. coroner released findings saying Murphy died primarily from pneumonia, with multiple drug intoxication and "iron deficiency anemia" as contributing to her accidental death. No illegal drugs were found in her system.
"Everything [surprised me and Brittany's mom about the report]," he told PEOPLE. "I expected [the cause of death] to be her heart."
Monjack and Sharon Murphy have said they believed Brittany's death was due to a congenital heart murmur, and denied rumors that the actress used illegal drugs or suffered from an eating disorder. They added that Murphy's heart condition was diagnosed in her teens, but said she had received proper treatment for it.
Monjack said Thursday that Brittany didn't seem very sick on the day she died. She was "not that ill," he said. "She wasn't coughing up. I've had pneumonia and coughed up handfuls of spittle. So yeah, everything surprised us, everything."
Asked about the coroner's assertion that his wife's death could have been prevented if she'd just gone to the doctor sooner, Monjack said, "I don't know what he said so I don't want to comment on what I haven't seen."
For him, a chapter has ended. "Case closed," said Monjack. "As the coroner said, there's no foul play."
Regarding concern from Murphy's friends that Monjack should be investigated, the coroner's Assistant Chief Ed Winter told PEOPLE: "He was never considered a suspect. No one's criminally liable here because this has been ruled an accident."