Need Some Advice

Any advice is welcome, and this will be a bit of a mess to read, so bear with me.

So, almost 2 years ago I met this guy. He was my best friend for the year that we hung out together. I had a massive crush on him and we were kinda more than friends but not dating (I'm sure you all know what I mean). We had some amazing times together, like when we were hanging out in a fire exit, sitting on the stairs and listening to Arctic Monkeys as he held me in his arms. He said things to me such as "even if we haven't been speaking, I'll be there for you" and "I won't leave you like everyone else did". I made the mistake of believing him.

One Friday night I messaged him because he was the only person I had. My aunt had just died and I really needed someone to talk to, but he didn't reply. He left me on read. The next month one of my other friends died and I messaged him again, and he did the same thing. It's been over a year since the last time we spoke and I miss him, but I feel like he doesn't even remember me. I know I shouldn't but I want to message him again, just to see what would happen, but I know it'd be no use. We met because of a girl at school I'm friends with, and I want to ask her if she still talks to him, but her and I aren't the closest so I feel like it would be weird. I just don't know what to do. I've been thinking about him so much lately, and it's been making me rather sad. I want him back in my life even though I feel like he doesn't care about me and he's forgotten about everything we had.

Anyone know what to do?