Hi Gilly83 - sorry not too much advice from me, but I wanted to wish you the best. I am in a similar situation and got lots of great advice from the lovely ladies here, but it's still difficult.
I was home with a sick DS yesterday and I found that even just 1 day off was such a huge relief (even though I had a sick toddler at home). Can you get your doc to give you some sick leave or something (even if it's just one or two days)? It might be enough to let you refocus on yourself a bit?