A hug between two friends is sexual harassment?

I am female and I was recently written up because a male employee at the same company I work at gave me a hug (he happens to be my best friend) and a third employee (female) claimed she was offended. 2 days after being written up I saw a copy of the original complaint she filed and not only did she say we were hugging but that we were also "making out" and that she didn't think it was right since the male employee is married and his wife, who also works at the same company, "could have walked by at any time." We tried to have the warning removed from our records since we were lied to, but HR and our bosses refuse to remove them and deny that she said the words "making out" in her claim, they also deny that her claim has anything to do with his marital status. I can not divulge my source because we would both get fired so I can not prove she said this. HR and my boss both refuse to show me a copy of the original complaint, stating that it is used for the investigation (even though there isn't one). HR and my boss say that the written warning stays since the hug created a hostile work environment for this other person. The male employee was also told it is sexual harassment. If I am being accused of this don't I have any rights? Do I have a right to see the original complaint? If you need more info on my situation please feel free to email me. Thank You.