If APS has opened an investigation, that is your best source for help. Otherwise, you can call the local bar association and see if they can refer you to a pro bono program. This site is not designed to deal with this kind of problem. Is there another adult you can trust that can help you?
DISCLAIMER: This is not specific legal advice and does not establish an attorney/client relationship.
Unfortunately, I don't see how an attorney can help your girl friend. You need to call APS or 911. This is a dangerous situation. If she might die, then the police should be called immediately.
You can certainly look on this site or the State Bar of Texas website for attorneys knowledgeable in powers of attorney, elder law, disability, and/or probate law. These types of attorneys work a lot with disabled people. However, they usually prepare paperwork for people. They are unable to provide physical protection for people. Again, they are going to call APS or the police of someone is physically in danger.
If your girl friend is being cut with razors then there should be physical proof. If she is not being fed on a daily basis then her body weight and her blood work should show this.
If she is scared then she needs to notify her medical care providers at her next doctor's appointment that she does not want to leave their office and that she wants the police to come to the office and take a report and she wants to file criminal charges against her caretaker. Doctors and all medical care providers are required by Texas law to report any abuse to the police or risk losing their license. Therefore, none of this makes any sense.