How do I move on from a 'highschool thing'?

So I've been in a "situationship/ almost relationship" with this guy for 4 years now. Before we had a thing, we were really close friends, until now. The more I hanged out with him, the more I realized that I love him. When we talked, we would make plans about our future together and everything. Essentially, that became my reason to work hard and to give myself a bigger push. We would pull each other up. Time by time, I realized how good we were for each other. We were both mature and responsible teens. Months ago, I told him about my feelings for him and he took it so well. We both agreed on staying friends.

Months later, I was doing so well and I was finally accepting that friends will be all that we will ever be. But, we saw each other again after a year during the graduation and all of my feelings for him came rushing back in. When we talked, he told me that he was going to take the scholarship for another university which is pretty far from mine and we had different schedules. Knowing well that he has always prioritized his studies above everything, I panicked. Academics was our common ground from the very beginning and it was fading. It sinked in to me that I'm going to start a life without him. My life, unconsciously, used to revolved our dreams with each other. For 4 years, he was there and I was. And I know I should let go but I keep on clinging to that hope that he will come back. I guess I'm just having a really hard time navigating life when everything in my life is going so bad and he was the only one that went right. He was my comfort. And I couldn't pour my love to anything else - my family, school, hobbies, myself. I just can't no matter how much I force it.

When we were both busy now with our works. He would always approach me on chat and talk to me about his feelings and experiences in his school. Of course, I would make time for him even if I have a lot on my plate because I never saw him as a burden. That went on for a long time. I made him stand back up to his feet again and again. One time, I was really having a bad day when I got my exam results and was dealing with family problems. I reached out to him and he said he was busy and as soon as he's done with his works, he would get back on me. It's been a week and there's still no reply from him. It sucks. It sucks loving someone who can never love you the level you could. It sucks putting in time and effort on someone who would never do as much. It sucks taking a 'highschool thing' way too seriously.

I thought that if I get myself out there, I'd meet more like-minded people. They were great actually but they all somehow feel the same. Nobody's words ever hit my heart or mind. He was just a unique person and he's everything I need and I'm looking for and it sucks having to let go eventually when our friendship fades. It sucks that no one will ever compare. I know I don't need relationships because I am so young but God was I genuinely happy and in-control when he was in my life. I don't know how to keep going on anymore. I feel like a robot right now lol. I keep on working and working but I don't see the reason why. It feels like there's no substance in my life. I probably should work on myself and giving myself a sense of direction but I have to get over my healing process first. But it is so hard! I'm sick of crying over our relationship for months straight. Just when I make a progress, I find myself falling back in to my pattern. I just want to feel okay and accept it. I have no choice but to accept it. But I still do hope we can try again in the future. See? I still cling into that hope.