TIME TO VENT.

Jennifer
Hi Guys, let me try to keep this short. 
Please bare with me. 
My name is Jennifer , I'm 20 and I have a job. 
I do not pay rent but I do help out whenever my parents need it, no questions ask and honestly, I love helping them out.
Then we have Viv. 
Viv is 36, unemployed for about 10 years and loves to stick her nose where it doesn't belong. 
She loves to lie. She loves to steal. She lives for the drama. 
She drinks vodka like water day and night. I wake up at 7am to her refilling her ice tray for her ice cold vodka. Refreshing. She started drinking because they took her car away for so many DUI's. She's gone to jail so many times. My mother cried so many times because of her. She throws huge tantrums because her favorite person died from a TV show or because someone stole her iPod. 
Just because I'm adopted she always tells me "she's MY mother" or "Be grateful".  
Just yesterday she changed the wifi password because she wants everyone to pitch in, which is understandable but she doesn't even pay for it either. Her girlfriend, who lives all the way in Hawaii, does. Her name is Nicole and she pays EVERYTHING for her. Concerts, dinners, groceries, the new iPad Air, the Apple TV,  bail to get her out of jail. Viv is not even faithful to her. Nicole doesn't even know who she truly is. 
I'm sick of living in this house with her. We can't have our bags out because she will steal our money. We have to hide our own food because she will eat it. My parents have to lock their door so she doesn't try to steal from them AGAIN. 
Viv knows my mother's social security by heart. 
Everyone here jusy acts like " There she goes again, just stay quiet or els it will cause a bigger problem." 
I don't know what to do or how to handle it. Sometimes I wish I can stoop to her level and play her little game but God dammit I'm an adult!
Thanks for taking the time to read this guys. I appreciate.