Gong Er, did she really exist?

I really liked this film and I am surprised for all the negative reviews?!
I am curious as to the authenticity of the story and if "Gong Er' really existed
or was this film part fact and part fiction?. Director Wong has a distinct signature in his films about a poetic view of journey of life. His characters encounters are very similar in this film as it was in his other film "In the mood for love", where the scenes in the streets when Ip man and Gong are talking for the last time.