Human Decency Is Dead

So I have had a crap week. Too much bad has happened and I am so negative right now that I have decided that human decency is dead. I don't even know where to begin. There has been so much that I don't think I could possibly write it all down. So instead I'll just give you the general idea. For the last 5 days I have had a person around me that has insulted me, lied to me, taken my things without asking (she has taken 2 pairs of my shoes, clothes from my girls, my phone, my kid's car seat, wanted to take my car, and came into my room while I was sleeping, took my work computer from under my bed and ran the battery down but didn't plug it back in), disrespected me and my hubby in our own home (she informed us last night that if she needs more than 2 weeks to find a place then she was staying at our house longer even though we told her she only had 2 weeks. She also took my cell phone and wouldn't give it back to me when I asked for it, she had the nerve to snap at me and say do you mind? I'm on the phone, I'll be done in five minutes.), ditched me with her kid (twice. And both times said that she would only be a couple hours and it was more like 4-6 hours both times), cluttered up not only my back garage (which was where she was supposed to put all her shit), but the front one (she unloaded a bunch of her shit into my backyard, left, and called my=e from god knows where almost 7 hours later to say that it was going to rain and that I needed to get her stuff out of the yard) and my basement (pilling up boxes and shit so that we can barely get to the bathroom downstairs). She has caused me so much stress that last night I about hit her. I wanted to knock her out so bad. She expects hubby and I to be at her beck and call, but she can't do a single fucking thing for us. She even went so far as to inform me that since the basement is now hers (which it is not. She gets to use the spare bed in the basement, nothing more) she was going to rearrange things and was going to take over my hubby's den in the basement. I told her that wasn't going to happen and she basically told me that she was doing it whether I wanted her to or not.
So basically I have felt used, disrespected, and pissed off for 5 days. Thank the lord she went away for the weekend. I needed the break. But I wish there was a way that she would go stay somewhere else next week when she gets back. But we don't want to be assholes and through her out (well hubby basically is asking me to try a little harder to talk to her about all this, but what's the point? She thinks she isn't doing anything wrong. I will hold my peace as long as possible, but I can't promise that she won't disrespect me again so bad that I knock her ass out.) nor do we want the rest of the family thinking we were in the wrong.
So that brings me to today. A boy I know was diagnosed with cancer. Tonight I am having a benefit movie night for him to raise money. I was expecting a really great crowd. I got maybe 30 people and raised maybe $15. I am so disapointed that I want to cry. Can nothing go right for me this week?
Why didn't I you ask? Because she is my hubby's little sister. She moved in with us until we could find her a place. It's supposed to only be for 2 weeks, but after 48 I wanted to throw her out. Unfortunately if this situation goes bad it could screw up my relationship with all of hubby's family. So I am trying really hard to be the bigger person and keep my mouth shut. It's just hard when she is being a demanding, unappreciative, selfish little cunt. So now whenever she is there I am going to stay in my room as much as possible so then she can't get to me. But I swear by everything holy that she will be out at the 2 weeks mark.