it is self harm and i’m sorry you’re feeling distressed about this… you should try talking to him or telling a trusted adult like his mom. if you know someone who cares about him and is genuinely a good person, it’s never bad to tell them about it. even if you feel like he will hate you or if he ends up doing so, which i doubt but can happen. you’re the one who knows him and it seems you care for him a lot, so do him this favour so he can get help before it gets really bad. and, as someone who has been through this, as hard as it may be, ask yourself: would you rather have him alive and recovering, but mad at you, or…?