Grief and loss (possible trigger drug addiction)

This is gonna be a long one I'm sorry. I lost my best friend two years ago. When he died he wasn’t alone he had some of his friends there (I don’t know if you know Lil Peep but my friend basically died in the same way) I can’t help but wish with everything I have that I’d been there that night then I could of done something but I also don’t know what I’d do if I was actually there and it still happened. I knew him since high school but because I dropped out and moved around we sorta lost touch. We got back in touch about 4-5 years after high school because I moved back to the area where I grew up and was living with another friend from high school. Hanging out with him was honestly the most fun all he wanted was for everyone to have good time and enjoy themselves. He had a lot of parties at his place I had never felt more connected and happy socially. After he passed away at first we sorta kept in touch but now I don’t hear from anyone anymore but I still see everyone on social media hanging out (before lockdown) I’m finding it really hard to move on from this friendship group because I just don’t understand why they don’t message me or ask to hang out. It’s made me feel very alone and question if any of my friends ever actually liked me.

I’ve tried not thinking about his death and distracting my self but then I forget about and when I remember it just hits me all over again. I miss him so bad, I’m lucky I got to see him 4 days before it happened, me and some friends were hanging out and I got to share some churros with him before he passed out asleep. When I left I wish I woke him up to say goodbye or stayed the night to see him in the morning.