@Swishyswash
I'm so sorry you are going through this.. I have a 16 year old and it breaks my heart to imagine him doing it.
But.. I will have to say although I feel the above I am a self harmer in times of great distress if I blame myself for it. It's something no one knows about me apart from my brother and my partner. My partner worked it out and my brother I told because he was doing it and in a bad way, so I felt I could tell him that I did and that things get better.
So now I'm thinking to myself what would have helped me..
To know how much it hurts the people I love would have made me think a bit more, because it's all about punishing yourself and a release of some kind. It does something to our brain that calms it.
It makes you angry because you love him and can see what he has to offer world and indeed what the world has to offer him. In his head he's stuck in a bubble, a bubble that doesn't let him see the real world and the bigger picture right now. No doubt the more he does it the more he hates himself, a vicious cycle.
Do you know of any underlying reason why? Weight issues? Stress issues ? Friend issues ? Self image?
He may just have the horrible low self esteem, so no matter how lovely they are, handsome, clever or popular they will not see it. Anti-depressants help, they help by lifting your mood, your feelings of love for yourself but the first few weeks can risk the opposite affect as it can make you feel worse at beginning. Sadly it's all down to self control in the end, stopping yourself, just stopping when you want to do it.
Does he self medicate with anything? Drink? Weed?
Drink makes self harming easier, gives you the balls to do it when alcohol has sent you into a spin of sadness.
Weed may mellow you out at time but the negative affect of bringing you down lasts when the nice affects wear off.
Even if he rejects you, continue to tell him you love him, that if he does that it breaks your heart, if there's something he needs to write it in a letter or text if he doesn't want to talk, so you can understand but the truth is he doesn't understand it either.
His brain is wired now to find something sharp when feeling bad, even to have it near by is enough sometimes to calm the brain.
Teenage years are such delicate times there really is a chance he can get over this. I would if he isn't already get him on antidepressants, they work, the up your feelings of worth but you have to be careful of alcohol with some of them.
Wish you all the luck in the world, it's so horrible to watch it happen to someone you love, anger is high because your emotions are high. Remember to look after your own well-being too.
If there is anything you want to ask me, feel free too.