I don't think you ever truly come to terms with it.. but you do learn to travel a path you weren't expecting, you learn to take things day by day, and even to enjoy life in a way that is different.
That sounds incredibly trite I know. I TOTALLY identify with wanting to know what it would be like, next year, when she's 5, 10, 18... that's exactly how I felt. I couldn't envisage anything but gloom and worry and despair (I was pretty depressed)
My son is 12 now. To be honest I still find every birthday gives me a few moments tears when I think about how things should be (he has three elder siblings so I have very clear comparisons) but most of the time, yeah we live our lives..and his existence has taken the whole family along paths we might never have trodden.
I now work in my son's special school, with severely autistic children . My summers are spent camping with internet friends who I met thro our shared need to meet others in the same boat.. I have made friends I would not want to be without. My children have grown into fantastic young people who accept and understand disability..
And my son.. well yes his life IS different.. ( he has moderate LD and autism) but HE's not sad about it..he sees the world his way and we embrace his world.
It will be ok...
In the short term.. seek support from those who will 'get it'.. here, other internet forums... make time for yourself; (it's easy to end up being chief carer, head cook and bottle washer and just be worn down)..
wine..
chocolate..
The grief and resentment does sort of pass.. it really does, although it pops up now and again..
It's also easy to forget that friends whose lives seem unfairly easy now, may have heartache at different times.
My youngest son dropped me into the world of disability.. but my able, beautiful, high achieving 15yr old daughter has struggled with eating disorder, depression ..parenting her has brought a whole different level of heartbreak.. you never know what lies ahead for anyone, and resentment takes up energy...
Hang in there..it WILL be ok