To lose a friend like that would make anyone feel terrible beyond words. If I had been in your situation I think I would feel horrible guilt and a mess.

It sounds like you have a lot of pain you would like to stop feeling, but you sound like you have people close to you, who would feel loss and pain if you weren't here.

I hope you will ask someone to help you find a therapist to help you with your grief, if you don't have the will to do it yourself.