I am so sorry that this is happening to your family, but you have done the right things in getting to the root of the issue. This should be a wake up call for your daughter, but it's going to take a lot of therapy for her to learn this. Do not forget that some people tend to test the boundaries and if you tell them they can't have contact w/someone, they will find ways to do it. It become a challenge and secrets begin. I hope your daughter will not be like this, but you will need to watch her behavior vs what she tells you.
Thank goodness school is almost over and hopefully her father will step in and work with her on this matter.
Thinking of you and praying that everything works out.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.