Maybe the cocaine was beginning to wear off and Jeremy had to confront the awfulness of his actions. Or maybe Julie was right at Blazers' restaurant Blackheath and Jeremy told her he felt nothing for the deaths. He was jealous of the twins which Sheila brought out to the tractor(and hence the "no comment" to Police on this piece of evidence)because his children had not been born when Suzette Ford had a series of miscarriages. Jeremy was going to even it out. In any case Jeremy had to be in control:it's why he stuck with Julie for so long and why he despised his parents so much as he began to understand that those who paid the piper called the tune.
I wouldn't take anything that JM said,as authentic at all. She was a gossip-monger who knew she'd gone too far with that mouth of hers. A loose tongue in a loose woman.Recipe for danger and that's what JB was. She wasn't in love with Jeremy.She was watching his every movement,,listening to his sometimes silly talk which she knew was at the time,,but elaborated latterly in court. Circumstantial evidence shouldn't incarcerate a man for 27 years,,,but she was the actress and she made it happen. Shame on her.