Cherished friend passed away

Ceira
Okay girls, I feel like I'm losing it. Mentally. We all have that group of girls who we consider like our sisters. Recently one of my girls passed away.. She was only 19. I feel so empty, I moved away a few months before it happened so it was hard to get together with everyone. And now all I can think about is how I got too caught up with work where I am that I missed out on spending all the time I could with her. I hate myself for it every time I think about it. I've been even more of a wreck since her funeral. It still doesn't feel real to me. I can't help but to feel alone even with my boyfriend sleeping right next to me. I feel bad for wanting constant affection in some way but I can't help it right now. I grow very attached to people and I feel as if she took a big chunk of me with her. I just want her back and I don't know who else to go to anymore. I know so many people are hurting so I can't throw my grief onto them as well.
Why is the world so cruel? To take someone as pure and innocent as her. I just don't know what to do anymore. How were you guys able to cope losing a loved one? I've never been hit so hard by someone passing like this before