I disagree that he ditched her. Her WS says she left him on the 27th August 1985 to return to London & her job. She then met him on the 4th & 6th September 1985 so they were still on speaking terms.
Her WS also says she tried to leave him earlier. But Bamber said he needed her.
Believe it is optimistic to expect Julie to jilt Bamber on the 7th August 1985. Then start speaking to the police on the same day.
She had to digest what she was being told by him & what was happening around her.
Bamber was still directing things, insinuating Sheila. The police and the relatives were giving him emotional support. Everyone accepting it was murder/suicide.
The relatives especially AE were on his case from literally day one more or less.
Stan Jones didn't like him from the outset.
Taff was still stubborn with his murder suicide theory.
Accept it have come as a shock to Julie ( depends on how much you think her involvement was /but even without Bamber telling her she must have been able to put and two and two together
She was composed enough to volunteer to identify the twins.
She was composed enough to spend time in the vicinity of CC, enjoying his hospitality. Knowing all along that she had knowledge of Bamber killing this mans children.
She supported Bamber at the funeral.