Contemplating not adopting

My husband and I took our FD into our home 21 months ago. We were not foster parents even though we had talked about it before and both felt that fostering was not in the cards for us. We were approached by my sons daycare about possibly helping out a little girl who needed a place to stay for 2 months until she was moved to her grandparents home across the country. The grandparents had already been approved for the placement and that it would be 2 months before they could move her. We found out about it Wednesday night and she was with us by Friday night. To say that we were unprepared is an understatement. She came into our home with next to nothing and we provided for her and that 2 months turned into 6 and 6 into 12 and so forth. We had some ups and downs with the state system, from case worker who did none of the stuff she was required to because they were going to go live with her grandparents to fighting with them to remove said caseworker. We have had 2 hospital stays for her, and countless dr. appointments and still have no records. They provide her services such as in home therapist and trauma specialist and just went they start making progress the state doesn't renew the contract. She has had 9 counselors in less than 2 years. Now we are at a point where dad is willing to sign rights over to us and we are having reservations. We have addressed our concerns with the state agency and they tell us not to worry it will work itself out. They told us that if it ever got to adoption that we would continue to receive the monthly stipend and that she would stay on the state plan for medical. Now that we are almost there they tell us well she has to be approved to receive the stipend and that she will most likely not receive the medical. I always thought once you adopt that was the end of all the financial help but they told us that in our state that a foster child is considered a child with special needs due to their circumstances and as a result would continue to receive these benefits. Our foster daughter sees 4 different specialist every other month all for things that were caused due to her neglectful parents and being born addicted to meth. That's on top of 2 physical therapy appointments a week, prescriptions and the fact that her mouth is going to need extensive work. This will all be out of my pocket if they will not continue to provide the medical. My husband and I decided together a while ago that even though we make "good" money we didn't want to have another child because we wanted to be able to afford to do things with them, and had we been told that these services would not be available and that I would be spending upwards of 300+ a month on her medical appointments we would have addressed this sooner. I feel that state services are trying to hoodwink us again. We have tried to transfer into a specialized foster program so that our daughter would get additional services and they refuse to transfer and insinuated that we were only doing it for extra money (not the case at all). Over the past several months things have gotten worse daily. For a long time things were going well and she was making huge strides, now she is failing in all her classes, she is stealing from the school (4 different times) stealing form classmates, hording food from my mother in law amongst a list of other things. My mother in law lives in an in-law attached to our house and that is where we spend most of our time, since it is connected to the playroom. Last Saturday my MIL went out with friends and before leaving she checked the snack situation to insure she had enough snacks for school. On Sunday she went into her closet and noticed a lot of items missing. She called my husband over and he was like mom you are losing she would never take stuff. We questioned her and low and behold she took the stuff. We went into the playroom and under the couch was 32 packages of snack gummy fruits, (18) eaten, next to the couch in a bin was 5 container of Pringles (3 eaten) and several packages of Oreo's again (3) eaten. How she didn't get sick I will never know. These were all taken on Saturday while my husband and I were on our side of the house cleaning. She has never done this before (that we know of) and I understand that this is something that foster kids will do when they don't know when they will eat again or get that snack again but I would have expected that month 1 not month 21. She knows we never deprive her of food and she always gets snacks. Needless to say my MIL is not happy nor are we, and she has told us our daughter is not allowed in her apartment anymore. Which of course is an issue for us. I work 2 jobs and my husband 1 and we often need her help getting the kids on the bus and watching them after school so I can go to my second job if my husband isn't home yet, now we don't know if she is going to do this anymore. Yesterday I received 5 emails from her teacher about stuff she is doing. She stole putty from a classmate again, stole from the library and informed the teacher that the reason she doesn't have a snack is because we are too busy and don't give her one. The reality is she ate the snack on the bus ride to school and then cries to the teacher for a snack and the teacher provides it. She made her best friend cry the other day saying hurtful things to her and when the teacher asked her about it she looks right at her crying friend and says I don't care. She lies over everything and will keep a lie going for hours. These might all seem like petty issues to most of you since I am assuming you have all been doing this for awhile but for us it is tearing us apart. My husband and I are constantly fighting with each other usually about stuff related to her. We are arguing with my MIL, and unfortunately we cannot do anything about that because she invested her money into the house as well and we cannot buy her out. My sister and I are currently not talking because I went to her for advice and we got into an argument. I am constantly in tears and feel like I am going to have a nervous breakdown. My work is suffering at both jobs as is my school work (3 more classes left...YAH) We caught our foster daughter shoving our nephew (2) across the entire playroom, and one time tackled my son because he picked up one of his toys and she felt like he shouldn't have it. She has started to damage items around the house and recently cut up the pillow case in her room and it was clearly done with scissors which we aren't sure how she did because all she has is safety scissors. I'm starting to get nervous that she might hurt one of the other kids. The hardest part in all this is that we are about 3 weeks away from dad signing his rights over so that we can adopt and then 90 days after that supposedly when they say we could adopt. We are struggling big time with this decision. We love this child and all we ever wanted was to give her a good life, but should we be doing that at the expense of our family? I am scared that if my husband and I continue on the path we could end up separated. I don't want to live in my house in fear that she could do something and I am starting to get to that point. I think she might have scissors hidden somewhere, even though we have checked everywhere and there doesn't seem to be a pair missing . She has no empathy at all, she will just stare you down and thinks that saying sorry will fix everything, which I know is typical for the age but she never learns from her mistakes she just continues to make them and continues to do worse and worse things. She also has no attachment to anything she never asks for her parents or grandparents. She never asks to see her sisters (at another home) and when she does see them her youngest runs up and gives her a big hug and she just stands there like a statue. Monday her therapist came to the house and had a graduation ceremony because they said they couldn't help her anymore, so again we are left alone with no resources. I know this is a long post and I apologize but I am truly lost. I feel guilty that we should have made a decision long ago, but things were not that bad then, and we kept thinking things would work themselves out. The thought that we are letting her father and grandfather down (we have met them through the course of her time with us) is bad enough let alone the thought of what might happened to her. I am having a hard time with the thought of what people will think fi we decide not to adopt, but its hard not to. Sorry Im rambling I just needed to get it off my chest and maybe here from others.