Anger at God is a central theme in your problem, desy.
Do you think an angry God took your son away from you to hurt you in some way? My Higher Power is not about anger or revenge or pain and suffering or shame or guilt.
My Higher Power is a comforter in hard times. A better Way in sorrow. A lifting of burdens.
I have lost all of my family. Every single one of them died. I am now alone in the world if I choose to be. I don't blame God, people die on this planet. Sometimes little children die of heart attacks. I don't pretend to understand the Why of the Universe.
I just try to live with what Is.
We may or may not get answers. I don't think the why is even important. Your son would not want you to live in agony due to his death. If you could commune with him now, do you think he would accept that it was his time? Do you think your son might say to you, "Dad, it's okay. I'm fine. Please live your life." ?
I had to get to the place where I believed my family is looking down on me and cheering me on, not looking down at me in sadness for their deaths. Their time came. So will mine. I am tasked with living life as well as I possibly can for however much time I have left. I don't want to disappoint them by wallowing in my sorrow. That's no life.