ah topic starter, it's clear from your question that you are
young or have not loved so deep that when it ends, your world ends
too.
i can't speak for all the "self-cutters" but i know some of them do
that as an escape from the emotional pain they feel. It's something
like this:
your eyes are dry of tears cos
you cried so much, your heart is hurting so bad from all the
beating it is taking. you take a pen knife, you let it glide across
your arm, a thought comes "if physical pain can relieve this
misery, even for a sec, i'll do it". you take the pen knife,
slowly, very slowly, let the blade do the purpose it was made for -
cut. you see blood, the pain from the cut overrides that of you
heart. for that moment, just for a moment, you stop crying, you
stop hurting. life becomes easier to bear.
If there is anyone out there who is cutting themselves, please pour
out your woes to a friend or a blog. Letting your emotions come out
would help you heal.