Hi Jules,
You probably won't even realise this but by you posting what you have, it has probably made many others feel 'normal'. By that I mean, many of us recognise your feelings and they are perfectly normal, natural feelings. Admitting we feel down, especially so soon after diagnosis, is something each of us has felt and even though I've had diabetes a few years more than you, every now and then I still get a bit down and beat myself up for not coping,mentally.
I am glad you have found this forum though, as you will feel supported, whether you are up, down or in need of just asking for advice.
It takes time to get your head round the diagnosis you've had but you will get there. Promise.
All the best,
chocoholic.