No matter what I try to do for Hayleigh, she ends up contradicting me, and we end up butting heads.

I guess it's my fault, really.  Ever since Jim left us high and dry, I don't want anything bad to happen to her, so I have indulged in catering to her every whim.  Guess I got what I deserved.

I can't seem to control her errant behavior.  No matter what I do or say, it is never good enough.  Hayleigh is also good at wheedling and promising to be good when she is anything but.

Hayleigh is my youngest.  Hayleigh is seven, and she's picked up a very bad attitude.  She has taken to sassing me at every opportunity; sometimes the arguing gets so bad, I end up in tears.

She is always butting heads with her older brothers; she will say to them, "You're not the boss of me!" and she is always tattling on them.  It is beginning to drive me crazy!!

Hayleigh has everything she wants; I don't know why she is oftentimes so angry.  I get calls from her teacher at school, telling me how unmanageable she is.  Hayleigh has become something of a bully and she picks on the smaller/weaker kids, much to my chagrin.  She's also failing in her classes, and she doens't seem to care for anything (or anybody) but herself. 

It's getting really bad.

If I could have some parenting advice on how to handle Hayleigh's "bad-girl" behavior, I'm all ears, and open to all suggestions!  Please help this desperate mother; I am at the end of my rope with my baby girl!