<wee hug>
You will manage - all of us with babies who Need Extra Things do, in exactly the same way as those of us with babies who Need The Usual Things do.
One of mine was very unwell for 10 years, he's fine now. I had to learn a whole heap of skills that I didn't want to even know about let alone be competent in. It was scary, and too much responsibility, and I was tired and upset and felt like I was the worst mother in the world.
Being sad and overwhelmed and resentful and angry is reasonable - your baby has been handed a really rough deck of cards and that is just unfair.
But, she has you. And you are going to be able to give her just what she needs, I know that because here you are already looking for some support. Lucky baby.
Here's what I wish someone told me:
get a knowledge network - you got a specialist nurse? Is there a charity for your LO's condition? Find someone who "gets" it so you can vent, ask questions and know that if you need to moan you can. Find out about benefits - you might be eligible for carers allowance or baby might get DLA. Find the hospital's family support people and ask for help with filling out the form, don't do it alone, it'll upset and you and there is a formula to the anyway.
get support - get a group of friends who can drop you round a coffee and kindness or sort pets or shopping or pick up the things that you are currently overwhelmed by. Or figure out how to outsource those things - cleaner, a gardener, supermarket deliveries, gym membership, baby swimming, massage, whatever - that's why you need to get the benefits you are eligible for, and spend it on what keeps you sane.
Have a very, very low bar for asking for help for yourself, watch your mental health like a hawk. If you go down, she goes down, and that isn't an option.
Might be worth speaking to your GP now and say what you did in the post - there might be resources or support the practice can offer, some run groups for parents of kids with extra needs, maybe the practice nurse can be a port of call, health visitor might be able to offer something, they will know of the local groups and online groups and what not.
There is a place on MN for "children's health" - even if you don't find someone with the same condition you are managing you might find someone with similar issues, or someone who can direct you to the right place.
get practical - what is the worst scene scenario you have been in, and what would have made it easier? Emergency hospital bag always packed and kept near the door, an extra long phone cable, a spare battery charger thing, a spare pair of reading glasses, a tenner's worth of pound coins, your own pillow, a warm pair of socks, an hour off the ward.
get cover - if you are sick/unable, who can take over? Don't be the only one in her life who knows what her medication regime is, what consistency her food is, how she needs to sit after eating, what her favourite teddy is, what the red flags are. Get a small group of people that you can TRUST. There will be time when you can't do it, so plan for it now.
Don't panic about other babies yet, you'll find your feet with this and life will look very different in six months, and then again in a year and before you know it you are looking at a giant with a beard. Well, my little dramatist is male, so maybe you'll not get the beard. I can send you some. He looks like a haystack. I can't believe my bloody luck.
Oh, and avoid people who want to send you that fucking awful poem about wanting to go on holiday to Italy and landing up in Holland or whatever it is. They can fuck right off.
Hang in there.