Hi Honey I just wanted to send you a huge hug. I know how it feels to be blamed for your child's issues, it's different but my eldest was 3 before they diagnosed kidney disease and in that time we were told we were neurotic, bad parents etc.
I guess in the long run, love you have to try to let go of the anger and injustice, just because hanging onto it makes you bitter and unhappy. Try to focus now on fighting for yor lad to get him the best possible treatment. I have 2 friends with sons with Aspergers and yes, it's difficult but they're both doing ok and much better than they were expected to.
Your brother, as much as you feel for him; he has to help himself right now. Try to narrow your focus down to what you can actually achieve and the first thing is to STOP with the crazy eating because you know you're hitting self-destruct big time. You DO NOT DESERVE to be punished for any of this, so DON'T PUNISH YOURSELF.
There is an organisation called CAP (Christians Against Poverty) who I do a bit of work with who may also be able to help you with your debt management. They are experts, do it for free and one to one, and you don't have to be a Christian or church goer to get their help. I'll have a look see if there's a centre near you who can help. Livinstone in Scotland right? Is that a big city or near one?
Much love and hang on in there sweetheart. You're not alone. xxx