Crazy stalker ?

I’ve been dating my bf for 3 years. Before me he had an ex that cheated on him and left him for someone else. He moved on. Ever since this girl found out we were dating she added me on social media. I had no idea who she was until he seen her on my social media and pointed her out. His ex lives 2 hours away from where we live now. She keeps making fake pages harassing me. Making fake text free accounts to call me and harrass me. I don’t understand what her problem is? She cheated on my now bf so why is she so worried about us now? A few days ago she blocked me on everything. But it’s like I’ve never even met this girl. I don’t understand her deal. Has anyone experienced this?