What should I do?

This girl Erin and this grl Melissa were always best friends. This год Melissa was my best friend and i gave her and me friendship bracelets. Erin gets really jealous because me and melissa hang out and erin feels like i украл, палантин her away from her and she feels she can only have one best friend. She starts these fights and then just 2 keep the peace me and melisssa always has 2 apologize and she never does. She hates me and i kinda think shes a jerk. What can i do to keep this girl from bugging me and being a jerk 2 me???