It's absolutely right what everyone says that to change she has to want to change.
It maybe that she cannot engage currently in camhs. But eventually she may see it's a need.
It may be that currently she thinks life will sort itself out however she behaves - but eventually she'll realise her behaviour will impact her life choices as it'll affect peoples view of her and her options.
Whatever the route cause of her behaviour she won't be able to change it until she realises it's necessary.
I really respect that you are supporting her victim and their family and acknowledging your dds behaviour and it's impact on others.
I think you've made the right but sad realisation that with regards helping your dd change it just can't be done whilst her father is heavily involved. You've tried to protect her from his influence but haven't had support.
And PRUs aren't what people think.
Most have different branches. There will be the classes/ branches for those with behavioural problems and she may end up in that. But there's also branches for pupils who are too anxious for school, cannot engage in large classes and also students with medical needs. They will assess her needs continuously and if she's out into the class for pupils with behavioural challenges but they notice the route cause is anxiety or similar they'll work with her and move her.
Forget education right now - that's a marathon not a sprint.
Her behaviour and understanding of that and it's 8yo acts on her victims and also her life chances has to be the priority right now and that's what they'll focus on within the PRU.
I think she's gone too far and has shown too much lack of engagement to believe a simple change of school will be enough to activate something internally in her to make her want to face her behaviour, the route cause and change.