Her ex-husband was supposed to be eating with the others who were poisoned (who happened to be the ex-husband’s parents and aunt) but he didn’t make it there.
Keep in mind, however, that this is a small regional community in Australia so the likelihood of people being part of extended family relations like this is much more likely to occur.
The ex-husband got very sick on a different occasion where he had a “mystery” bout of severe gastroenteritis where he was in a critical condition and put into an induced coma and at two points his loved ones were brought in to say their farewells to him because they thought that he wasn’t going to pull through, although after a few weeks he managed to recover.