I Miss Someone That Doesn't Miss Me

He was in my life for a year and a half, then he just disappeared. Ghosted me like I meant nothing. So why do I miss him? I was completely vulnerable with him, I had never opened up to anyone in the same way I had with him. I feel like a fool. Re-reading messages that mean nothing. Why does it hurt? Why do I care? I moved on a long time ago... or so I keep telling myself. I guess I wanna know why, but I'll never find out. I bet I haven't crossed his mind even once - that's what makes me angry. I know I'm unimportant and worthless, but to be reminded of it in this way hurts.