How can I stop the defamation from my previous employer?

I feel that I have been defamed for several years by a previous employer. This is evident to me by the behavior of the co-workers in the companies I have been working in. I think my previous employer is stating that I harass people even though I hadn't been written up once and wasn't fired. In the background of different assignments I have been in, I have heard supervisors ask my co-workers if I was harassing them and telling them not to harass me. Also, I remember at one assignment last year, an employee at the company saying that if I were to say anything about sex, race, or use profanities or expletives, the police was going to be called. This has happened repeatedly at different assignments I have been at. It seems that my co-workers have purposely used expletives and have made comments about race just to see how I would react. I know if I had said the wrong thing the police would have been called. I know there are rules about defamation suits, and I think there is a one year statute of limitations in defamation suits. I am just trying to avoid a false arrest from taking place. What is the best solution in this case? This has caused me a lot of mental anguish and frustration. I have tried reference checking companies, but they don't work.