Oh, man, I know exactly how you're feeling and it's shit. It's so hard, and you have done so much already and you're knackered, and it all has to be done again tomorrow.
And to be honest, what's being asked of you right now is crazy hard - in the history of motherhood, it's never been the norm that we work full time AND breastfeed AND do all the sleepless nights AND do it by ourselves in a tiny single household without a community of other people around to lend a hand. It's insanely hard, especially when your friends aren't there yet. They will be in a few years, and you'll be there giving them advice, but unfortunately when you go first in your friend group they're no bloody use to you.
Look, first things first, yes of course it will change. Motherhood isn't just the baby phase, many many things will be easier a year from now, and two years, and five. But that feels a long way off from here. You need some support right now. Dreaming of going to hospital, just so some other bugger has to look after you for once - I've 100% been where you are, but it's not good and it's a red flag that things need to change in the here and now. Not everything at once, but something, to get you a little rest and the strength to change the next thing, and the next.
There are a few things you can do, and it's up to you in what order you feel able to tackle them.
Get signed off work for a few days, you are not well, it's not skiving. Better a few days on sick pay now than months, when you have a breakdown.
Talk to your OH. How much has his life changed since you had your son, and how much has yours? Breastfeeding makes it go that way, to some extent, but don't let it be the pattern forever. Time for some honesty and a big reset.
Think about how long you really want to breastfeed for. There's nothing magic about the 12 month mark, except being 'allowed' to switch from formula to cows milk. A few weeks early won't affect anyone in the long run, honestly. It's got to work for you, too. And if he's a bottle refuser (mine were - solidarity, it's infuriating), you can express and let DH give him breast milk on some weetabix while you stay in bed. Anything for an extra hour of rest.
Think about how you can change your nights (I know, it feels impossible). He settles for you because it's always been you, right? But it doesn't have to stay that way, let DH get up and weather some screaming if necessary. Or let them watch Bluey at four in the morning, if he won't settle - you need sleep too. DS can nap at nursery, you can't nap at work.
Look at work patterns. Could you do a compressed week, work four longer days and one day off to recover yourself? Or use some annual leave to give yourself time for a think?
I know it's hard. You're doing great. Pick one thing when you're ready, and start there. Hope you have a better day today. And congrats on your lovely son.