Goodbye, My Danish Sweetheart

Lately I've been struggling with grief I've been suppressing for two years. Not over a death, but still over the loss of a loved one. Maybe it's the lack of closure that makes it hurt like this. Maybe all grief is the same, as I know I'll still never get to see them again. I'll never get to see their artwork or read their writing. They're gone for good, and I largely feel like its my fault.
I was 14. I didn't know how to react with a situation like that and I made it worse. I didn't mean to, but I did. I am constantly plagued by guilt, knowing maybe if I was just a little smarter or a little less foggy, this never would have happened. They would still be here, and things would be the way they should. No good has come out of this. Nothing but suffering and guilt and a pain like I've never felt before.
I dig my nails into my scalp and bite my hands, never managing to cry for more than five minutes. I can't. The walls of my house are too thin, so if I cry for too long or too loud I'd surely get caught. I can't sob like I need to. I want to wail at the top of my lungs for their loss, but all I can do is hyperventilate until I dry heave from holding back tears.
Even though this is one of if not the most painful things I've been through, there's something about this I find almost addicting. When the pain of the moment subsides, and I stop crying, there's nothing left but numbness for the rest of the night. Nothing but tiredness and sometimes a desire to be alone.
I think there is a strange beauty to it, to love someone so much it ruins your life to have them torn away from you. If they were around to witness this pain, they would know for a fact how much I still love them. But this love just can't reach them anymore. It floats around and squeezes my heart until it feels like it's going to explode. Where will it go? I can't give love meant for someone long gone to someone else. As much as I love my friends, and I love them so much it hurts--they can't fill the space that was left. No one can, no matter how much I love them. I wonder what they would think if they saw where I am now. I've come so far, but I've also lost so much of myself.
There was a third person in our group. It was just the three of us. I still talk to the other person a little bit, not as much but they still mean the world to me. But they've been acting like such a jerk lately. I've been watching them turn into the kind of person I wouldn't want to be around and I don't know what to do. I can't just leave them. That would be disrespecting our friend's memory. That would be letting go of them by association. It was just the three of us for so long. We were so close--I third wheeled them sometimes, but I didn't mind. They still did their best to include me. I miss the times when we were each other's world. When we thought we could accomplish anything together. We had so many plans, so many promises. But that world we built is still crumbling no matter how hard we tried to keep it together. This wasn't fate. This wasn't predetermined. It didn't happen for a reason. It's just a tragic situation that came from a mixture of bad luck and bad decisions.