Everyone is dofferent and that goes as far as self harm, some people self harm in secret while others need to confide in someone that they feel they can trust to tell that they do self harm and not to judge them and tell them that they are wrong or cowards for choosing their method of coping. Me personally i have attempted suicide 3 times and each time I have told someone either before hand or while i was waiting for the affects to take hold, it's a combination of a last cry for help and just plain reaching out to someone to talk to and you should NEVER diminish the reason why someone reaches out to you as them just seeking attention and playing mind games with you. NEVER.
And try not to call the police on people, especially mentally ill people or anyone in emotional distress, the police are not trained in dealing with mentally ill people and most of the time an interaction with mentally ill people, even ones who call the police themselfs because they fell they will hurt themselves end in the death of the mentally ill person at the hands of the police. If you're worried about someone, contact another friend who lives close by to drop in on them and check on them.
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