I'm so sorry for your loss, Johnor. Praying for you and your family.
We never really know why things happen for sure. Try to remember that we are all put here on earth for a reason though and that it isn't our permanent home. It could just be that he had completed the tasks that he was here for and is being rewarded by getting to be with his dad in his permanent home. Also try to remember that you are never given more than you can handle. It may seem like it at times and it may require the help of others, but you can and will get through this. ((Hugs))