^^ I agree. Just remember that there are two sets of feelings involved here. There are your own and then there are that of your gf. Assuming you haven't told her, she's giving you her 100% while not knowing that she's not getting the same in return from you.. And trust me I been there, recently, i'm still there actually. In trying to get over my first real love I met someone, someone who actually loved (or maybe even still does) me. I kept going out with her even though I didn't quite feel it with her. I always subconsciously said to myself that she was nothing compared to my ex gf. So one night when I slept over at her appartment we went to bed and I was holding her until we fell asleep... and unbelievably... I dreamt about my ex WHILE in bed with my gf. I felt happy and I was smiling when I woke up, until I realized it was not actually my ex that I was in bed with but rather my gf and thats when I was like wow this is not even fair. I felt so bad.
So when I got back to my place, the first thing I said to myself is that I have to end it right now. In your case you don't necessarily have to do the same but you do have to be up front with her about your residual feelings. But anyways I called her up and I told her that i'm not ready for a relationship right at the moment and i'd like to take a step back and become friends. Of course, she asked me why and for the most part, I can't really lie to someone when they ask me a direct question. So I told her that I really like her a lot, but that my heart is still trying to get over my ex and i'm not really ready to date as of right now... She was all kinds of angry and hurt, told me i'm a player, i'm this and i'm that... but regardless it was the right thing for me to do. I don't blame her for getting mad either, because in a sense I actually WAS playing her despite it being completely unintentional. It is certainly playing a woman to commit to her when you know you are in love with someone else.
Be careful with your heart, because when someone seems too good to be true, they usually are.