Growing up is hard to do!!

So this week Brittany came home early from school and she looked as if she was crying, so I asked her what was going on? She said with big crocodile tears, "I don't want to grow up" after she said this I thought to myself. I didn't know what to do or what to say. So I didn't say anything except let her talk. She is 18 years old and she's already an adult. I thought to my self that she has been through so much already in her 18 years of life than I have in my 31 years of life. So time passes and she asks dale and I to go to town for little things and I said "no" because I just got done with work and it was my fourth 12 hour shift and I was tired. She got all mad and said "If I lived in town, I would just go where I want to go." So again I didn't say anything because I did not want to argue with her for I was too tired to make a big deal out of the comment. Then she made the comment that this summer her and her friends are going to move into an apartment together. Is it so bad I thought to myself, that it not quick enough. I guess sometimes I just want to get on with my life. How terrible is that?? Thats all I can say is that she lies to us all the time and I am getting to the point where it is too much to handle..
The next day I read her blog and she writes that she is living in a prison and she misses her home and family. I thought to myself, "Dale and I aren't keeping her from seeing her family or friends." She has our car she can go if she wants to see them. We don't tell her one way or the other if she can see her family or not.
I just thought how terrible is it living with Dale and I. We actually spoil this kid. She can talk us into most anything unless she breaks our trust which she has done many times in the past 11 months. How can she say things like this when we care for her and she writes the only thing important to her is her cell phone and her friends. That is just a teenager talking.
So today I looked on her school attendance and seen that she skipped school 2 times last week. How upsetting is that, we give her a car so she can go to school and work and she skips school anyway. How are we supposed to trust her. She doesn't care how she treats Dale and I, but we are supposed to care how we treat her. She has terrible character. I can't trust her and I don't think I ever will. I just don't know what to think any more..