Hi, sorry for you are going through. My daughter was diagnosed at birth with a very rare genetic condition. It's incredibly tough, and I can relate to how you are feeling. The life we thought we were going to have is not happening. My daughter has had multiple surgeries, ITU admissions and has lots more to come. I felt the same as you in the beginning, you grieve the life you thought you were going to live, and the life you wanted your child to have. I also carry a lot of guilt for the impact it all has on her older sibling.
All that said, it gets better. Your find your own "normal" as a family. My daughter is 9 months old now and she's a smashing little girl. Full of smiles and brings so much love and joy to our family. I won't say her condition doesn't bring It's challenges, as it still does and always will, to her and all of us as a family. But once you get your head round it, it is just normal.
Is your daughter under a specific hospital? My daughter's (extensive) team include psychologists who keep in contact with us regularly. If you can access anything like that, it could be helpful- they've also said they offer help and support for siblings as they get older, too.
My only advise would be take any and all help and support offered to you. I know they get a bashing on here, but my health visitor has been worth her weight in gold to us. She's referred us to services we would have had no idea existed and to baby groups for kids with additional needs which feels easier to take her along to than usual ones.
I don't know your daughter's condition, or how rare it is, my daughter is 1 in about 80,000 births, I think, and we've found a Facebook group - small as it is, about 150 of us, who have kids with the same condition, which has been helpful for feeling less alone. If you can find any charities for your daughter's condition, that might be something else to consider if you wanted any more information or support.
It's crazy in the beginning when you first get a diagnosis, but it does calm down and I promise it does get easier.