Please Help!?

Recently my best friend (let's call her c) took a trip to Arizona. When we got back one of her ex friends ( let's call her w), that hates me told me that throughout the trip c was ranting about how I was getting on her nerves and that she didn't even like me. Of course I thought w was just being jealous and starting drama. She then went on and told me things c told her about me and our trip that she wouldn't know had c not told her. She told me even if she hates me she would look out for me because c had used her. I don't know what to do?