Don't play her game and you will win her back. Ignore her and have no contact with her and she will run right back to you. Some women like a relationship where there is a challenge. Some advise, there's a country song with the chorus, "Ain't it sad when Mr. Right comes along and you're stuck with someone else"
Love doesn't hurt, love is not cruel, and love doesn't play games. You don't deserve what is happening in your relationship!!! There is someone out there that is going to want to see you smile everyday. You can't ask to be placed in someone's heart when they have no heart. She sounds like she still has some growing up to do.

Dear Heavenly Father, in Jesus name I ask that you bring clarity to this relationship so that if it is meant to be, they move forward and if it is not meant to be, guide this person so that they may find the blessing they truly deserve. Amen