Bloody hell, that's horrible! What a truly terrible thing to happen, on all levels: the injuries, the shock, the stress, the fear, the fact it was your own brother.
I wish I could offer advice, but all I can say is work it through and you'll come out the other side somehow. And yes, you can post here. People should always feel like they can share their fears and worries. Doing so itself is part of what will make things better.