i know it must be hard for you to concentrate during work, when you mind is not with you. but you need to focus, work is work. and when off work, Hardcore play time... What done is done, wat lost has lost. Just try to move on. Also, you do need to experience other girls. No matter how special that girl was, she's not yours anymore and will never be. So take your time to forget and move on.
She is being truthful about having ZERO interest in developing anything with you and at least has the decency to tell you so. Taking all the gifts and money from you does not mean she feels anything for you. In fact she probably feels justified in accepting your gifts and money given that she didn't lie to you and stated her position over and over again.
So focus on your work for the time being and your feelings for her will subside over time.