Hi,
I dont have a teenage daughter. My sister does. My sister left her husband when her daughter was 3. Her ex has been a B*rd in all sorts of ways, daughter still had to on holiday to him etc so as not to violate access arrangements.
Recently my niece started saying she wanted to go live with her dad. In the middle of teenage angst, tantrums, she suddenly decided she wanted to live with him, and she was arguing with my sister daily about this, ranting and raving, threatening and sulking, skipping school and what not.
In the end my sister said to her: Fine, you go. I will ask your dad to arrange school for you so can start afresh next school year.
THEN, my niece started thinking. About how he actually treats her when she is there, how he is forcing her to read philosophy books rather than Harry Potter, how he insists she plays piano rather than swimming lessons (which she loves), how he insists that she should go to after school maths and science club instead of sports and friends, etc. How he is forcing her to empty her place totally because she is so skinny.
And then: Mummy, you dont really love me if you let me go live with dad. How CAN you even consider being without me?
What would happen if you let her go?
Now it is your daughter and your EX against you, making your daughter the martyr, the centre for attention. He gets a change for a mega battle with you again, and she is in the middle.
Sorry no advise, just my perspective. And what do I know.