Your not my real mother!

This is a long story and I will try to shorten it. We are foster parents, have adopted two and have four in guardianship. We have never treated our guardianship kids any different. I have no bio kids and my husband has two that do not live with us. This year has been rocky! We had a foster child a girl (13 yrs) for over a year. She started to become violent with us and the other children and I finally had to say enough is enough and ask them to move her. I do not regret that. However since I did have her moved she started claiming all sorts of things. We hit her, we beat the kids, and so on. All of the findings are "unfounded" according to the state, but we have been told we will not be able to foster again because "once people think you may have done something, even if it is unfounded in their minds you are guilty" (My licensor said that). The problem is all of my kids know about this so now when two of them (boys 10 and 9) get into trouble for anything they threaten us! I gonna tell them .......... So tonight these two got in trouble for not doing chores, the were told that if they did not want to take chore time (5-6 pm even though chores only take 10 mins) and use it for chores then they loose free time (7-8 pm) and can go to bed at 8 pm instead of 9. One of them immediately threw up "your not my real mom" and the other followed suit. Then the first one started claiming that earlier when we were all playing with light sabers (star wars) that I hit him with the light saber and he was going to tell when he goes to school tomorrow. Now I have been told by the state that I can not photo graph or video tape these kids (the guardianship kids) because they are foster children but then they also tell me they are not foster children (basically they are foster kids as long as it is convienient for the state but if not then they are not foster kids) so to protect myself I called the police to come and look at the child so tha I have a witness that there is no abuse. I was told by the cop that they usually do not come out unless the child calls, but when I explained about all the false reports he did come and look. When he asked the child to show him his shoulder the child said "I dont remember which shoulder it was" to which the cop said then it obviously did not hurt that bad. The problem is I do not know what to do, the state has given my children all the power. Everytime they get in trouble all they have to do is make a false report! I could not believe it when my son (adopted) stated I am not his real mom. And then when the guardianship child said that I will admit I was wrong I said "your right I'm not, I love you more and will not leave you" I should not have said that but to be honest I am just worn out and past my limit! Any suggestions???? Thanks for listening Pamir