Stuck on High School Crush

I am literally losing my mind. I’ve been out of high school for 3 years now and am still very hung up on this guy I had a thing with on and off Freshman-Junior year. It was pretty platonic with a whole lot of feelings. He was your typical “fuck boy” but somehow we always got back to each other and his best friend use to say he never saw him as happy as he was with me. Our “thing” ended for good when he finally put himself out there and asked me out officially, and I turned him down. The next relationship I got into was with my current boyfriend, whom he was well acquainted with and it obviously bothered him. I found something I wrote about him years ago about how he helped me through my depression and how much he meant to me and it really sunk in that I think he was my first love, and he still means so much to me.

I still see him around sometimes and every time I feel my heart beat in my ears and get like a butterflies/nausea feeling. We’re both in relationships, mine for 4 years and his fairly new. I still think about him often and I even have dreams about him. When the song I had for him comes on I still get in my feelings. To be clear. Times have changed since then, I do not want to date him, I am not attracted to him, I don’t feel any physical✨ feelings for him. WHY DO I FEEL THIS WAY? It feels so wrong and stressful, and I feel like I really need him to know how I feel, but WTH 5+ years later out of the blue?? What do I do so I can stop losing my mind😭