What are my rights?

I am under review by the HR Dept. regarding an incident with another employee. Recently, I tried to assist a co-worker, who is known to behave in a dramatic manner, and she became upset. She was not upset with me but with the thought that I was withholding information from her. I tried to talk to her personally, like I have done many time, and she began crying and behaving foolishly. I touched her arm and tried to reason with her but she then screamed for me to get the f*@! out of her face. I then turned and walked away. Other nurses in the nurses station witnessed the event and one threatened to call a security because the other employee was screaming and using profanity. The upset employee then called the Unit's Director and began telling her about conversation between she and I. Again, she was not upset about my contact with her rather the information she thought I was withholding. The director was out of town so she called her supervisor who is now accusing me of violating Texas Penal Code. Please understand that the person I had the incident with does not feel in any way that I assaulted her. While being interrogated by HR I realized they are trying to fire me and they are telling me that every other person who witnessed the event, tells a different story from myself. I know that to be a lie because I saw the other letters and they agree with my version of the truth! HR refuses to explain the inconsistencies with me and they tell my that I am not charged with assault and battery but my behavior fits under the criteria and that I behaved inappropriately. I have a friendly, personal relationship with the employee and she does not feel threatened by me in any way. Also, she has had issues within our unit since she hired on. I have never been reprimanded and my evaluations have been superior. I believe that nepotism is partly responsible for this situation because the HR dept chooses to believe the explaination of a personal friend over the explaination of 4 other witnesses. Can I fight for my job and win? I have not been terminated but I believe it will happen based on the behavior of the HR Department. They are very vague with answering my questions and when I asked about the inconsistencies of the reported incident, HR responds that they do not have to tell me but I should be aware that my version contradicts the other witnesses. I am sure for a FACT that the other witnesses did not give conflicting accounts.