I feel like i'm overly sensitive?

i'm a straight girl and I feel like i'm overly sensitive and obsessed with one of my friends(she's a girl). Everything she does affects me in some way and I don't understand why. if she ignores me or when she's mad at me I take it too personally and I get depressed. I love it when she gives me attention because I feel like she's showing me how much she cares about me. I don't know why but i've been getting depressed because of my friend too often lately and i'm afraid that she'll leave me alone because I love her so much and she's been there for me and I don't want to ruin or friendship because of my obsession with my friend. what is wrong with me? what can I do to help myself and stop taking my friend so serious?
PS:This only happens with One friend. Thankss xx

In very few cases do people make close friends for life. Most often it's more like a movie where new characters come in and others move out of the picture. Set some goals for yourself that are yours alone and work of them every day.