How come I can't get over and stop being sad that my closest friend who is a girl got married?

I have a friend that I've known for about 5 years and I used to have a crush on her but it faded away about a year and a half ago. Then today I saw her uncle at his sandwich shop and he told me that she got married and I did feel a little sad and disappointed. I lost contact with her about 6 months ago after she changed her number and never told me her new number. She is only 19 and she is married and I'm 20 and never had a girlfriend because I cannot get a girlfriend. What can I do to overcome this ??? It's not an extreme sadness that is driving me to extreme depression but it does make me feel a little depressed. I just lost a close friend because she is married now and also lost contact with her as well. Her uncle did not tell me her new number, it seems like he didn't want me to know it.