letting go the desire for a person

Hi. I am a diamond but never did any work on intimate relationships yet. There is this girl I fell in love with a while ago, and I have found myself thinking about her unceasingly for the last months. There is no chance that the relationship will develop, but my brain still thinks so. I am ready to let the desire for her go but I am not sure how to. For the moment I have been writing down some thoughts that generate desire, which more or less are “It would be amazing if she could be here”. What kind of thoughts would you suggest me to try to lower down the desire progressively? Thanks