Death threats in perceived same sex gay bashing messages being left by a coworker

I begin to see these messages in my office and work area and at first thought it was just one of the guys joking with me here at work. However, as the days passed, the messages begin to increase in the amount that were being left. Soon they changed from just name calling to uneasy threats and then to death threats. I'm curious to whether I I have a case here or not of sexual harassment and/or defamation of character? I am not gay, in fact I am married and have been for 28 years & together we have 4 children and 3 grandchildren. I have not reported it to my employer due to the nature of the messages. In hopes that he'd stop. They've only gotten worse. It's affecting my work. I cannot focus clearly sitting here reading this crap! I'm so upset and ashamed at how all the other guys on his shift have given me the cold shoulder. I worry how this has affected my reputation. Please help soon.

Thank You!