I'm still hung over this girl what should I do?

Long story short I found out this girl I knew liked me so I asked her out three days later I break up with her cuz she only likes me as a friend it wasn't a big deal the only part that made me kinda mad was my friend had to tell me like she couldn't have done it herself but anyways almost a week later I feel really desperate for her and I really miss her I don't get why I feel this way