Who am I

I'm your greatest nightmare and I haunt you as you sleep,
although we two are strangers we've a bond that runs so deep,
i am the one who contradicts each single word you say,
and the one on whom you can rely to fuck up your whole day,
i'm the one from whom you cant escape though every day you've tried,
and the one who did destroy your esteem,confidence and pride,
to be your lifelong enemy on me you can depend,
but you'll never be alone with me i'm with you til the end,
do you know the one of whom i speak?if not please tell me why,
that you donot have the answer to the question 'who am i?'
if you haven't worked it out yet take a look and you will see,
that the person in the mirror looking back at you....its me.