Devastating news for all involved. So very sorry that you are having to go through this, and that his wife and daughter as well. So many questions are unanswered...
We lost a son twenty-two years ago in different circumstances, but the loss was overwhelming. In our situation, we held on to two things, three, really:
1. One day at a time. Get through today... just do the next thing - whatever it may be - even if that is breathing. In the Bible, when the Israelites were wandering, God gave them manna each day for that day (except twice on Friday for Sabbath). He had them rely on Him daily.
2. Grieve. The fact that you loved him and now he is gone is going to cause you to grieve. You may be fighting anger and questions and doubt everything you ever knew right now. That is natural, let it run its course but do not let it run your life. There are times to 'be strong' for the sake of others, but you need to grieve. It gets ugly sometimes with the crying and hopeless feelings. It is part of healing, so allow it to happen. Even if it's when you are behind closed doors and you completely lose it. Let it rip. Grieving helps you heal. IT TAKES TIME. You won't ever get completely over your loss, but - and this may sound uncaring at this time, but you will laugh again. Someday. There is hope.
2. a. Grief is too heavy to bear by yourself. Find someones to help you carry it. Your wife, friends, family.
3. Higher power. We read scripture and prayed like never before. God will reveal Himself and bring you 'the peace that passes understanding.' Soak up His words. Remember, He when He created the world, it was good, good, very good. It wasn't until sin entered the world that it started going downhill and death came into the world. God is able and He wants you to lean on Him.
If I can be of any help to you, please feel free to message me.