Emo is a branch of music formed from punk...It is usually emotional and has heart felt lyrics written about things from the writers own experiences..That's usually why you can relate to it so well...If you're not of a poetic mind though you probably wont understand of word of it.
If you're really sad you can go on ask jeeves and type in "what is emo" it will give you a whole list of pathetic sites made up to take the piss....Although some have accurate portrayals of the emo status
See also "straight edge"
www.straightedge.com