I'm in a similar position to phlebas.
something I have seen people on this board say time and again is that the pre-school years are the hardest. obviously the dx is in process or still raw.
and the grief that goes with that - the realisation that the life you thought you would have is gone, never to return, and that the life you have now is one full of uncertainty and battles.
I too just withdrew from everything. there was one toddler group I used to go to (used ot force myself to sometimes) when dd1 was smaller - I had started thee when she was 15 months or so, and everyone had got used to her, really. then we moved (for dd1's education) and that was no longer available. and I couldn't face starting at another group - dd1 was rising 5 by then, and to begin all over again with people getting to know her etc was too much to face.
most of my friends are still child-free. and so I don't moan to them too much -they can't even begin to understand, and anyway, children are a pretty boring topic to those without children at the best of times. so I have mostly lost touch with all my friends too.
life was just a lot easier, in so many ways, when I did not have to face the world and other people's children.
I think I am cautiously getting over that now. dd1 is nearly 6. she is finally well settled at an excellent SN school, so that battle is over (until annual review )
and now I turn around, and dd2 is starting pre-school in September. where did all that time go I feel as though she has been cheated of her babyhood - endless rounds of form filling, tribunal preparing, house moving, etc. and now she is so grown up.
we have had no help from SS at all, ever. we are about to employ a nanny (and I thank god we can afford to) to try to give us all some space at times. to give us the opportunity to go out without dd1, for both her sake and ours, and more importantly for dd2's sake. she deserves soem time that is not all about dd1.
but, like MrsT, I suspect those first few outings will be more full of sadness and regret for me than anyhting else. sadness that my life will not ever be "normal", and that, as dd1 gets older still, there will be fewer and fewer "proper" family days out, because meeting the needs of everyone will not be possible.