I’ll never hear from my best friend again

My best friend and i met online probably just over a year ago. I know that doesn’t seem like a long time but it was some of the best time of my life. we went through a lot both of us laughed cried grieved. Recently about a month ago she messaged me because she was “leaving” and didn’t want to leave me in the dark. I told her how i supported her no matter what. I realized when i saw everything suddenly deleted she meant all her accounts. I don’t know what she looked like or more than what state she lived in so it’s just sinking in that i’ll never see or hear from her again. I only know her first name and our memories from when she beat cancer to when i got accepted into college and she was the first person i told. I feel like i let her out of my life without eve fighting because i didn’t realize what she meant and now i only know regret that i didn’t even try to find a way to keep contact till it was too late