Re: totally lost
It's going to be very hard for a long time. I would strongly suggest that you get your son into therapy. He is at the angry stage which is common after losing someone but he is going to need help because he doesn't have the life skills to cope with this.
As for yourself, it is hard. I lost my mother in April. My father has kept busy but there isn't a day that goes by that he doesn't cry for his loss. You may want to take some family leave time from work. It would give you a chance to really look at what has happened and then prepare for the future. Going right back to work was hard for me and I am a daughter. I had several days when I was at work and I cried. It's taken almost 4 months and I am starting to be able to cope again.
Take the time you need. Get your son into therapy so he can get some skills to help him cope with his loss. And understand that you are not alone in how you feel.