Jakey, it's not your fault and it's almost certain that nothing you did or didn't do made any difference at all. I know just how you feel - I had a mc just under 2 weeks ago and I went over and over everything in my mind. I kept thinking "what if I'd rested more? what if I hadn't done this? Or that?" But probably nothing would have changed the outcome. Whilst they might not recommend downing a bottle of wine, I doubt very much that caused your miscaariage. With my elder daughter, I didn't know I was pregnant - we flew to Italy where I got seriously drunk every single night -bottle of wine a night - before I found out. She was perfectly healthy. This time round, I rested, took all the vitamins, ate healthily, avoided alcohol and caffeine - and miscarried at 9 weeks. So please, please don't beat yourself up. It wasn't your fault.
I know how you feel about letting your family down, too. My family were all so excited especially my parents who are in their 70s and were thrilled at the thought of a new grandchild. My two girls have cried buckets since the mc, and my OH is not coping well. I feel I've put everyone through so much upset. But, I wasn't to know it would end this way, and nor were you. Maybe you should think instead, that, at least for a little while, you gave them something to help them through the worst of the grief over your brother.
You've been through a truly awful time; a miscarriage is bad enough without it coming on top of other grief. But things will gradually improve, for you and your family. I am only 12 days on, and although I am still very sad and still crying quite often, I'm in a much better place than I was even a week ago. You will never forget, but you will eventually cope better with it.
Don't worry how often you have to post on here for support. If you are still struggling, hospitals can put you in touch with bereavement counsellors, and seeing as you've had a double bereavement, you might find that helpful. I think they would understand because they deal with this kind of thing all the time. I'd think that's worth asking about.
Take care and be gentle on yourself. xxx