How can I move on from my ex boyfriend? please help :(?

About a month ago my boyfriend broke up with me. We just weren't seeing eachother very much and he just recently got a huge ego. it hurts because I stayed with him through so much stuff and he went rough a depression a few months into our relationship but I got him out of it and really helped him through it. We were dating for a year and a month, and he wanted to marry me when we got older. Even though we've had no contact besides a friendly group message "Happy Holidays," everything reminds me of him and we have a lot of mutual friends. I still feel like he's a big part of my life, even though he no loungers loves or even cares about me. He was my first love. I'm 14, btw. I just feel so Lonely and upset. Basically the only time I'm truly happy is when I'm hanging out with my Ex's best friend. He's so awesome, and is more distant from my ex after we broke up. How can I get over him and be happy again. please help, :( and happy new year's everyone