How do i get rid of a Bad friend

My name is Seun I sent this story so that people can advise me on what to do and this is how my story goes. I am someone that loves to help people and I am also a very friendly person so I have a lot of friends but there is one particular one out of my friends that is very close to me. I help her a lot but despite all I do for her she is very ungrateful. She goes behind me to spoil my name and say all kind of things to people and even our friends. Things that are not true.

My family have called me times without number to warn me about her whenever she hurts me. But we get back and continue our friendship in no time. I love her so much. We have been friends for six years. Yesterday I met someone for the first time that was trying to start a relationship with me. Immediately I told him my real names he asked if I knew someone by my friend’s name and I said yes. Then he told me all he has heard about me and my family which were mostly lies. 

I started crying and called her on the phone. She said she knows the guy but denied telling him anything about me or my family. I don’t believe her because this is not the first time this will happen. How do I live without such a friend. Please help.Comments are welcome