Why doesn’t my frenemy leave me alone

I have a frenemy she has slept with a guy I dated, she attacked me physically because I found out about her sleeping with him, she blasts my business on Facebook. But she still always wants to be friends with me? What is her deal...my best friend thinks she has some jealousy issue with me..but I’ve been nothing but nice to her and she still continues to watch everything I do. I’ve forgiven her after attacking me physically for her mistake! Every friend that we have in common she thinks I’m “stealing” them because they hang out with more. Why doesn’t she leave me alone I’ve made it clear’