I've Made Mistakes In Life

I've made a horrible mistake at work today..an unforgivable one.. i just found out :( I have no excuse really other than that i am so tired.. but it was stupid to make a mistake like that :( I have been working 11-12 hour days for the last few weeks - I can only think i have got to the point where i am just so tired i am making mistakes :( I am not happy about that as i hate making mistakes at work.. i feel so bad about it - i'm competitive with myself.. i like to be better, stronger, faster and super-human even tho i dont expect that of others.. so i really hate it when i fail and do something wrong...
I think i will be glad when i am not working such long hours :(