Do you think Julie should have phoned the police after Jeremy woke up her entire house to say 'everything is going well, something is wrong at the farm'.
Perhaps she thought Jeremy was dealing with it. It was his family and he was only 5 minutes away from WHF.
What I think 30 years on is quite irrelevant. However, what Julie may have thought then can possibly give us a clue about the things which motivated her.
She was an intelligent girl. She would have known how to think and what question to ask. Giving her the benefit of the doubt, it may be that up to the point of THAT call, it had been an intellectual jigsaw which she can't NOT have thought about from time to time, but she didn't ask the questions presumably because she'd rather NOT know the answer. Better to think he liked to say shocking things. I CAN understand why she wouldn't want to believe he was serious. Who would?
His call, at the time of night it came, HAD to have changed everything. The last piece of the jigsaw must have fallen into pace and it's at this point that any sympathy I'd previously felt for her is diminished because I think it was here that she made a conscious decision about what course of action would deliver the most for her, putting her own wants above the lives of his family. I resolutely believe that if he'd married her she would have said nothing.