There is one new staff who stays in our department so my coworker taught her many works

She went to other department back biting about our department how our department dont work properly, dont support her etc and etc when the coworker of my department is the one who is teaching her everything how to work. Today I told her in her face that "Oh I remember when Suhana was back biting about our department and our department people with other department". And told her that she shouldnt back bite of people who taught her so many work and told her to have some work ethics then she was crying and wailing like a kid when I only showed that how she behaved. I guess, she just saw her ugly personality in the mirror which I showed her. 😈