She's gone straight up evil bro.

Tell her the following: keep seeing the news reporter girl. I was never into her. But you are and I dont care to share my partner. So you're off the hook. Do whatever. Just don't get me involved, dont ralk to me ever again and good luck in your life.

Smth like that. Break up.

Also talk to your co worker. Talk to her and ask her what happened. You need to make peace with your coworker cuz shes the one youre gonna be seeing daily even when you dump your bitch ass evil psycho manipulative should-be ex