Single mom frustrated with impolite teenaged daughter

Hello, I am wanting to move out of my own house lately or buy a shed for my daughter to live in. She never has a polite tone towards me, is always arguing with absolutely everything, doesn't seem to care about anyone but herself. This is extremely difficult for her older aspergers sister and younger brother. I understand where she is coming from but she doesn't even try to change. I am at my wits end so to speak. Please help, I know she needs to feel important and she is special but doesn't think so because her siblings are more needy and take more time away from her. It is only me here to try to give everyone a fair share of myself. Eeeeeek! Thanks for anything you can help me out with. I have no supports, can't seem to find and/or keep any and no family to speak of. I am trying everything! Signed, Feeling Helpless