North Carolina employment and sexual harassment law, hostile environment, employer's liability

I have been sexually harassed at work twice by two different individuals. The first person was given a warning and told not to talk to me. I was told that this was company policy to give a warning the first time, even though he admitted to what he said. Then the case was brought up during a union meeting with the supervisor (I was not around). He said he did not fire him because there was no witness! Why do you need a witness when someone admits to something. Now I have been sexually harassed again. I don't not feel safe to return to work, because I work on a lot (sometimes by myself) and this predator will be there. He is 20 yrs older than me and i am scared what he will try next. They said I have to come back to work, but they admitted they could not protect me 100 percent. What should I do? Because I feel like they don't care about my safety. Can they fire me for not coming in because I feel like I am in a threatening and "hostile" environment and Im not being taken seriously!