This lady is slandering my name and making it hard for me at work.?

I was helping her niece with her school work for the past four years, until her father died last years. After his death this lady started trippin on me. she had threatened to put ppo's on me and things of that sort, she lies to my pastor at church. I have been keeping my distance, I don't even attend my church because she goes there, I was introducted to the family thru her and her daughter who reached out to me four years ago as a big sister. But once her niece got attached to me and I started helping her,and showing her how to become a lady. that when things went south.She recently sent an email to one of the schools that I work at and told them she don't want me there and not to give me any info on her niece. Now it's affecting my job, I might loose my job and I really like what I do. What do I do?