I hope you have access to some sort of counseling. Grief counseling would be ideal.
The trauma of losing one friend is immense. The trauma & pain you must feel at losing several, at any age, must feel unbearable.

I am so sorry for you loss. It is not your fault.

Yours is a strong heart. You have managed to seek help in this very sad time. It is a good sign that you are willing to step back and assess what has happened.

Strong prayers for healing are coming your way...