You're letting this child set the rules. Bad move. Really bad move.

My husband was the same towards my SS when we first got together and my SS was the same age as yours. We had literally the same exact problems that you are. Once I saw how the SS started playing both birth parents like well tuned violins, I put an end to it in our house. As a result, in our home SS behaves beautifully and shows respect for both humans and animals, eats what he should and sleeps where he should. At BM's home, it's the exact opposite.

Giving the kids control soon translates into complete lack of respect towards all adults and believing the world revolves around them.

You have the house, you make the rules. Period. She'll cry and act out, but not for long. Kids love structure. Give her some.

Wow he needs to get control of that and fast. As far as going out with your parents or others, go alone do not take them with you and tell him they will not be invited until she learns how to behave in public. For her not cleaning her room, well give her one warning, it is cleaned by the time she leaves or whatever is left out is to be thrown away by you after she is gone (worked on my skids). As far as the trash under the beds and what not, take the bed frame away and leave just the mattress then there is no where to stuff the trash under there. More seriously you need to tell your boyfriend either A) he gets his child under control or YOU will and no matter how much he fights with you about it you will do it anyways and he can just get over it.

I wanted to really examine your issues and disect them.

"My boyfriend on the other hand will cater to her and let her eat chips and cookies and whatever she wants just so she doesn't go home and complain that daddy doesn't feed her."

Tell your boyfriend to man up and be a father.

"She started screaming and crying over this. I was embarrassed because everyone was staring at us. And my boyfriend didn't seem to mind. This happens EVERY time we go out in public...to the point that I won't go anywhere with them if I don't have to."

Remove the child from the restaurant and go home.

"She terrorizes the cats to no end. But every time she comes over they hide all weekend because they hate her."

Cats don't know how to "hate" a child. They hate the lack of calm in their home. Put the child into a time out.

"No matter how many times we tell her to clean up her toys before she goes back to her mom's, she won't do it."

Then you don't get into the car until they are picked up.

"she still continues to shove trash under the couch, under the bed, in her toy box, anywhere but the trash can."

She eats only when supervised and the trash is thrown into the proper receptacle by her when she's done.

"She refuses to take a bath/shower."

Let her stink. It will eventually sink in. Or her mother will cave and teach the child to wash.

"I don't know where it comes from, but I find opened candy stuck everywhere."

Check her overnight bag (or whatever) when she arrives, remove the candy, to be returned to her when she's given back to her mother. Do not keep candy in the house.

"She can't sleep without the TV on. And no matter how many times we turn it down, she turns it up so it's blaring loud."

Remove the tv from her room or put a block on it so that she can not turn it on without adult supervision.

"She refuses to sleep in her room."

Why is she given the opportunity to sleep elsewhere? Put her in her room, return her to her room if she comes out.

"She makes up the most insane lies about what mommy lets her do."

Why do you care? You should be concerned about her behavior at your home and how you can help this very disturbed child become a good human being.

"I don't feel comfortable disciplining her, but I do have to enforce some rules."

It is your home, you are allowed to have rules and enforce them if he isn't. No one should make you uncomfortable in your own home. No one.

I just married my DH in March of 2010 after almost 10 years of dating. I have a BD and SD that are both 13 and a SS who is almost 12. We have had issues from the very beginning with SD and are now getting some fun from SS. I have very different views on how a child should be brought up (much the same way that my parents raised me) and enforce my views with my daughter. I have tried to influence DH, but he really doesn't come through with his parenting. This is the very reason why-even though we are married-I have maintained my own home...separate from his. I am not saying it's for everyone, but it's what works for us. We had planned on not marrying until the kids were all out of the house, but I started getting worried about them never leaving!! (hee hee!) I have gone through all levels of the hated "step monster" disease. I came from a blended family that had it's rocky times, but we stuck together! I'm not sure if it made me naive to how bad a blended family could be. I thought if I just try to show these kids that it's because I love them that I set rules and boundries, that they would understand and we would all ride off into the sunset. Not so much. They have "that" kind of a BM (can't really even call her that since both skids are adopted)--the "friend" not the parent. Not too long ago, she came into my DH house and accused me of abusing SD by constantly calling her "fat"..which I don't do, but it's only one of a million lies told by this damaged girl. She then proceeded to call me every name in the book (scared my own daughter badly enough that she had dialed "911" on her phone "just in case"). DH wasn't home at the time, and BM was gone by the time he got there. However, nothing ever came of it...all the lies that have been told...there is never any reprimand. Half of DH's family thinks I'm a horrible person because of things SD has said...even if they bother to ask me about it...they still end up feeling like they have to be loyal to her, so I'm the bad person.

All that to say...you really should think about moving out on your own and getting your thoughts together about the relationship with your boyfriend. Is that relationship worth the rocky times ahead? Because I can promise you--unless he has a huge change in his ways...the little girl will only get worse. Is that what you want in your life? My own SD is about 6 inches taller than me and outweighs me by about 30 lbs...she has a violent streak in her that matches her BM and there is nothing I can do to make her mind me if I want to send her to her room or anything else. She has told me to "shut up" and since I have heard her call her own BM a b**ch, I can only imagine what she must say about me!! It is my own path to walk and I chose to do so after some very heavy praying...I believe that God put me here for a reason. I don't know if it's to save my DH or to save my skids....I only know that there is a reason.

Pray for guidance...ask for help and be strong! This is your life and you have to make your own choices, but stand strong in those choices!!