Hi, I'd like to help you with your question.
There could be two things going on for this girl. One, she is traumatized and is acting out as a result, possibly to gain attention. Two, she has not been disciplined and therefore acts out because there are no consequences to her behavior.
Most likely, her acting out behavior is a combination of both the trauma and the lack of consequences. It is good that she is getting therapy. This will help address any trauma issues she is having. The acting out behavior, however, needs to be addressed by a parent.
Consequences need to be equal to the acting out behavior. At her age, punishments can range from time spent in her room (all computers, music, etc removed while she is there) to having privileges taken away. For example, if she talks back, she spends 15 minutes in her room alone. If she does it again, then it's 30 minutes. The punishment increases each time she does it. If she refuses to stop, then she goes to bed. Make sure she is fed and all homework done then off to bed. Telling kids that their punishment will fit their behavior usually helps them understand that they need to make more mature choices about how they act.
The key to having children follow the rules is to stick to what you say as a parent. If a parent says no cussing and the child cusses, then the parent must punish them. If they allow the child to cuss one day and they do not punish them but then punish the next time it happens, it sends a confusing message to the child. Consistency is the key even if it is very hard and the child gets upset. Children need guidelines and rules in order to feel secure and to know that someone cares for them.
I hope this has helped you, Kate