Your ex boyfriends new girlfriend

I'll cut to the chase. His new girlfriend decided to search for me on social media, request to follow me and then start online fights with me. At the time of accepting her friend request I had no idea who she was. I don't understand why I am even relevant anymore I don't exist in his life. She gains nothing from attacking me in a clichè cyber bully attack. I literally called my ex and told him to tell her to get over her shit and he agreed he thought it was annoying too. What is this? Is this jealousy? Why is she jealous what is there to be jealous of? Neither I or him give two flying shits anymore. In her posts it's her comparing us like "I'm better than you" all at the same time I think it's rather funny it's also really freaking  annoying. What do you think? Is she jealous? Or just a nutcase?