Feeling Stupid

I feel that I am so stupid, after someone told me that thing I should not do..I have let the person down, i don't realise it until it comes to my realisation. Since when my sensitivity has gone below the standard level, may be its exam and alot of things going through in my mind, but if giving this kind of reasons, all these are just crap and I can't accept that even by myself...Someone has entrusted me, but yet I feel like i have betrayed someone, this gonna take some while to forgive myself, though that person probably had already forgiven me...Probably its a lesson to learn from? Guess I am just being over familiar. I am really sorry to whom you know you are...