Everyone is right, it's better not to start down this path. You might start off intending to do little damage, and then get out of control before you realise. I have scars that will never disappear. Don't do it to yourself. You deserve better

Do you have a therapist? If not could you get one? I wish I had sought treatment sooner...

Like Puzzclar suggested, use exercise to get past any urge to SI - it'll boost your mood, too.

Best wishes