Feeling hurt

How do I process the feeling of hurt?
How does a person know the true validity of their feeling? What is the purpose of the emotion hurt? What’s the benefit?

My situation is so high school like. I feel hurt because my best friend hasn’t called me in the past week and a half. And I realized that a majority of the time I’m the one calling her in our relationship which makes me feel like she doesn’t care about me. Which I know is completely not true especially since we been there for each other through thick and thin for the past 20 years. I just feel so bad that she is not thinking of me and wanting to call me.