Whatnext - you are in no way a failure. You have had a big trauma to deal with, been in shock, have a lot to deal with and a lot of recovering to do. You are having some time off work as a break in order to get things sorted and to recharge your batteries. Where is the failure in that? It's just pure common sense.
We all have times when we need to regroup, rethink, recharge our batteries, we all [most of us] have some sort of bad thing to deal with. We all deal with what life throws at us differently.
IMHO you need good food and rest, time to grieve, time to think, time to deal with practical issues, time to get help. There needs to be some support system in place, find a support group or a counsellor, plan days with your son, arrange times to talk to friends etc.
This is a good opportunity to find out about anything you can get involved with in the community in the future, any classes etc. - when you feel able to, of course not before. But make little plans, small reachable goals and daydream - a holiday, a spa day, anything you like doing.
Get tomorrow over, and see this time as a chance to feel a bit better. I know it's clichéd but it's always darkest before dawn, without rain there would be no flowers. You will blossom one day, just hang in there, you are coping and lots out here wish you well.