Your ruminations might not have as much to do with this girl as it does with you are not where you would like to be in your life. A good way to move on with your life is to get invested and enthusiastic about it. If your depression is being treated, then it is time to do like kaliope suggested and get involved in new things, especially ones where you interact with people face-to-face. Who knows, maybe someone new will come along in the process.