How to help a teenager with disfunctional parents

A couple of years ago I helped out a work colleague who had been arrested for DV. As it turned out, both him and his wife had had years of alcohol related issues and they were both as bad as each other. She has done the same things he has done but less consequences. He’s narcisstic and flicked me off in the end but I got close to his daughter as the “cool auntie”. He did actually ask me to have her stay at one point because they didn’t know what to do with her. She loves to come and stay with me and she can talk non-stop for hours, as opposed to staying in her room and only coming out for food at home. Her entire life is on-line at home.

The girl is now 13 and has been bullied at school and sexually assulted aged 11 by a boy who was a friend of her brother. I haven’t spoken to her dad apart from at work for close to a year and he is too toxic macho to be friends with me again. Anyway, the girl has not been at school for a few years now but she is extremely bright and mature and does her schoolwork on Google Classroom.

I don’t initiate contact myself but she knows that I’m available to her. Last week she tried to self-harm and called the police as soon as ahe did it. The next thing she did was message me to tell me what she’d done. I have messaged her dad and told him that it’s fine for her to come and stay but he’s radio silent.

I really don’t know how to best deal with this. Her dad is a narcisstic asshole who spent the best part of a year living with me telling me I was his best friend then flicked me off because he doesn’t know how to do friendship, and his wife is a nut job who saw a bottle of perfume in the background of a selfie the daughter took and immediately accused me of sleeping with her husband.

I want to help the daughter but it’s so effing difficult because neither parent has a clue and they just can’t communicate. The girl has put me on her contact list with her psychologist but the parents have cut her off from her best friend for some reason, and I am afraid they will think that isolating her further is the best way to deal with the situation.

What should I do?