I need advice on how to handle someone that lies about everything?

I have been a live-in caregiver for a woman who is only a couple of years older than myself (she is 48) for the last 6 years. I took this job because my husband had gotten out of the military and we needed a place to live and this was work that I had done for years in a hospital setting. When taking this job I was told she has the mentality of a 10 year old. I am her 8th caregiver in 14 years. 4 years ago she decided she no longer had to listen to me, that she could do what she wants when she wants. Her guardian told me not to argue with her. Her lawyer told me not to argue with her. So for the last 4 years I have been doing what I can to get her to take meds, shower, even brush her hair. There is nothing physically wrong with. In fact since I have been here I have gotten her healthy enough that she went from taking 9 different meds twice a day to only 2 pills a day. The doctor cannot find anything wrong with her.

The major issue I am having that scares me to death is this: She has started lying. Her last doctor's appointment was with a different doctor in the practice (one who doesn't know her or myself), she told him that I wasn't feeding her. He later called and apologized saying he had to believe her until her blood test came back because a lot of elderly people get abused. She isn't elderly but she acts like she is. She has told people that my husband and I beat her. She has told people that I am stealing her money, and I have no access to her money, I am just the caregiver. She has told people that my husband is poisoning the tap water. I was actually not concerned by the lies until she told her lawyer that I do not allow her in the living room and that we never take her out. Now the lawyer wants to get involved. I get inspected every 6 months to make sure I am cooking and cleaning properly. She literally walks through the whole house. I have to write a report on what I do from the time I get up to the time I go to bed. I have to do a financial report on OUR finances. Her finances get audited yearly - which has nothing to do with us, we have NO access to her money, I couldn't even tell you what bank she banks at. I am given $700 a month from her guardian and that is suppose to be my pay ($500) and money to cover what she needs. We pay all the basic household bills (Electric, water, sewer, cable) and buy all the food and toiletries as our rent.

I need help figuring out what to do to keep her from getting me into trouble. We do not abuse her. She does not miss a meal. In fact she seems to use the lies to control us. Do I get a lawyer? Do I get the doctor to verify she isn't abused? I have started taking picture of her meals (that are date and time stamped). And I keep a detailed calendar of what she does and what she says. But I feel like that will not be enough to protect us.

I can not get her to shower, brush her teeth or hair. She refuses to take her meds. She will not get up before 11am and will go to bed as soon as she is done eating. No one can eat at the table with her (She says it makes her nervous). She will wet the bed. I have watched her walk past the empty hall bathroom to go pee in the floor in her room. And her lies... she literally lies about everything! Most of which are mean and horrible lied. I don't know what to do. I am so stressed and scared that she is going to do or say something to get my into trouble. Please... any advice would be soooo appreciated.