"You know how I lied to you about my husband for you to have sex with me. Yeah, I'm gonna have to fire you for that. Also, if you tell anyone why I fired you i'll say you raped me"

So about a month ago I had a casual encounter with my boss. It was completely consensual on both sides. At the time my Boss was separated from her husband and claimed she was going to divorce him so she wanted to "have some fun." Well, everything was fine until today when she asked me to resign. She made it perfectly clear this is because of the one night stand we had. She claims she is getting back with her husband and doesn't want a "bad influence in the office." I told her no but she says she's going to terminate me anyway. Afterwords she texted me telling me that if i dispute it at all or come out about the casual encounter she will go to the cops claiming I raped her. I'm furious right now. What can I do legally at this point?