How do I tell him I knew as much already?

My friend (J) is so cute. We were talking the other day about my eating habits and stuff and turns out he went online researching them for me...Came back to me today and went '~X~ I'm dead worried about you, you have some form of an EDNOS and I think you need to get some help, you can get over this, you can beat it, I'll help you, I want you to eat with me at least 5 times a week and I'll be checking your weight.'
I'm wondering how to tell the poor boy I already knew as much? How I can tell him that I won't be eating with him at all, he won't be seeing my disgusting weight, because even I don't want to see it. I mean, I'm grateful he's actually taken the time to check up on me and stuff, it shows he cares about me, I'm not just one of those passing friends we all get. But, How do I tell him that actually, my restricting and my counting and everything is part of me? How do I tell him I don't want to give it up, because if I do, I'll have no way to escape things, and everything will just...Pile up again? How do you tell someone that cares about you, that this 'ednos' is normal to you? I wish I knew... I told him he'd be waiting a while before I ate in front of anyone, and that if he tried to stick me on a scale I'd brake his jaw bone. He told me they were typical signs to indicate I have this ednos... I told him I was self-concious. He didn't believe me. I wonder what he'd say if he knew about everything else...He'd probably commit me to a mental home personally. He mustn't find out, he must never know. I have to try harder to act normal. I'm obviously not trying hard enough if he could find out about this, why would I even talk to him about eating?! I'm so stupid. I need to get some control back from these ribbons, they've taken over me, taken my control, its difficult to do anything now, difficult to hide anything, because I don't have any control over myself, the ribbons do, and they like to see me make an ass of myself. I'm in so much trouble if he tells my Mother, I told her I was over all of this 'eating crap' as she called it. I don't know what to do, Help?! Bye my Angels <3