I have had a look at the other thread too. Nothing in there to suggest she is a candidate for prison.
I also had to send my daughter away at 16 after a year or so of mayhem and chaos. I am not going to suggest it was easy, it was a dark time for all of us, but
We are now out the other side. I used the time when she was gone to recover and to work on myself. I did one to one therapy and a group thing for abuse survivors which was basically about finding your voice, being assertive. I did two parenting courses, one for younger children and one for teenagers. Both helped me so much.
Gradually the stress fell away and my confidence grew. My daughter started getting in touch more frequently and asking to hang out. Then she asked to come home which we managed by agreeing on ground rules.
She finished school and found herself a good job.
She has worked through some stuff and is still tackling other things. She is as able to let some of the stuff go when she got used to me being more stable and consistent. She started to trust me more.
I am a much better parent for all we have been through. I learnt to look after myself and that helped me be in better shape for the children. They could let go of some anxiety.
Of course I wish I had already been a great parent and that my daughter had had a much smoother upbringing but here we are.
I suspect your daughter has complex needs, part of her distress will be to do with being a teenager and all the hormones and drama that go with it, some will be to do with her being neurodiverse, and some will be about her home life.
I know you mean well but all those different parenting strategies must have been very confusing for her. And she’ll likely to have strong feelings about the fractured family set up, feelings she may not understand or be able to express.
She has gone now, use the space to get yourself into a better space. Its the best way forward for you and all your children.
It’s perfectly reasonable to feel bereft. Feel the pain and keep going anyway. One day you will wake up and realise life is much better.