What happens when a professor makes damaging comments about another in front of students?
I am sorry this has happened to you. I have observed this at my place of work too. The poisoned well around you will make you sick. I suggest you get out fast and use our remaining dignity to find someplace where you are appreciated for what you do. Your boss or other colleagues are unlikely to help you because the writing is already on the wall that you are suffering negative consequences of someone else's unprofessional, jealous, petty and just plain bad behavior. Unless you are a mean street fighter, best to dodge this battle and understand that even if you win, this colleague will not change their behavior and likely cause future trouble. Do you really want to face that for the remainder of your career here? As fas as I know, this type of harassment is not protected by laws. Even your friends at work will not want to be involved as they will fear the wrath of this nasty person turning on them, if they speak up for you. I am really sorry. You sound like a sincere person who is doing their job the best they can, but it is hard to contribute well when so much of your energy must be sapped by fighting this stupid battle. Find yourself a nurturing place. The world is bigger than this narrow well.