I would assume that you also have Depression, no? (I'm not saying that is the only mental illness sh can originate from) .Try healthier coping mechanisms, for example drawing on your skin where u usually do it (with a red pen to imitate the blood if u use a blade) , a rubber band (I know it doesn't hurt as much but bear with me ) .Try journaling your feelings , (AND SUICIDE IS NO ANSWER)
or express the feelings u usually release while sh in art , I mean drawing or painting what u feel .Try talking about it with trusted friends who would understand and if you can try getting a therapist ( wich I would highly recommend) but if u don't have any friends try online friends.If the Situation is rlly serious and its starting to become an addiction and you feel like you need professionell help try talking about it with a trusted adult , teacher or schoolcounselor but the thing is schoolcounselors will in most situations not keep their mouth shut and there's a big chance parents/teachers might hear about it.It will get better , belive me .There will be a day you'll look back at your past self and be happy that you were able to quit .
or express the feelings u usually release while sh in art , I mean drawing or painting what u feel .Try talking about it with trusted friends who would understand and if you can try getting a therapist ( wich I would highly recommend) but if u don't have any friends try online friends.If the Situation is rlly serious and its starting to become an addiction and you feel like you need professionell help try talking about it with a trusted adult , teacher or schoolcounselor but the thing is schoolcounselors will in most situations not keep their mouth shut and there's a big chance parents/teachers might hear about it.It will get better , belive me .There will be a day you'll look back at your past self and be happy that you were able to quit .