I think it is great that you love her and that you are willing to sacrifice yourself in order for her to be happy. I am no expert at relationships, but I will tell you from what little experience I have, that self sacrifice in a non-mutual relationship will not bring much benefit.
I was in the same mindset as you during my previous relationship, and did not wish to hurt the girl I was with by leaving her alone and releasing all my attachment to her. But if the relationship is not mutual and beneficial for both parties, loving the person unconditionally and moving on is the best that you can really do. Every situation is different, so you must judge it for yourself, but don't let a relationship that doesn't serve you drag you down.