Thanks everyone
I totally understand where he was coming from when he said that, scared to see me do that to myself. I wouldn't want him to, there's been two occasions where he's been so hurt and distressed that he self harmed, he'd never done it before and I was heartbroken to see him hurt himself like that. For him, it never turned into anything, it was more a heat of the moment thing, whereas with myself this is how it always begins. Starts off small, then ends up becoming out of hand.
I felt I had to say something in case he saw, in case I slipped up and also because no matter how hard I try to hide anything from him he always knows if something isn't right. I don't know how he knows, but he does. I've always been able to hide this and everything else from everyone, except him. It's odd, we seem to know exactly what each other are thinking without having to say a word and I've never had this with anyone before.
I told him, he often has to drag things out of me because I want to protect him from any stress or worry. He was very different from how I imagined, he wasn't cross. He was very understanding and listened to me. The only thing I did think he'd do which he did was blame himself for it. He said he should have stayed awake all night to make sure I was ok, but I said that was ridiculous because no one can stay awake 24/7 and it wasn't his fault, it was me, I did it no one else.
It was silly of me to make that promise that I'd never do it again, I should have instead said that I would try not to but that I might not be able to help doing it.
Glad I told him, it's a weight lifted. Felt like I'd cheated on him!