Dreams and Nightmares

You told me you loved me and I was the only one,
You told me you would cherish every memory that we made,
You told me I was the woman of your dreams,
No other could compare.
So why did your dream of us become my nightmare?
Why can’t I erase the vision of you making love to her?
Why do I keep reliving the nightmare of you,
Whispering I love you in her ears,
Telling her she was the love of your life.
Now I keep wondering if she is the love of your life,
Then who am I?