I had an affair with a coworker (outside my work place), her husband found out about that and now he is threatening me about going to my job director with a taperecorder of her wife admitting that she had an affair with me.
Can I get fire for that?
What should I do
It refers to the "at will" doctrine which in shorts an employer or employee may terminate employee with or without cause with or without warnning. Long as the firing violates no existing law, cba or, employment contract. None of those appear in your post. For better understanding type "at will doctrine" in your search engine