Dear NL
I do sympathise - I recognise your feelings completely. My first DD was premature and in a SCBU for six weeks. The first weeks after she came home were among the worst in my life, awful though that is to say. I felt bizarre, not myself, totally rocked and thrown and utterly in a surreal nightmare. I remember pacing the floor at 2am with a grizzling infant, a complete stranger, a hostile one it seemed, looking out at all the dark houses around, and it seemed as if I were the only person in the country awake and struggling with this alien being. I certainly didn't 'love' her - in fact I wished with all my heart she could go back to the hospital - I felt strongly that she had come home before she was ready. It seemed I hated being a mother, and yet I had always longed to be one.
Well, the good news is that that little stranger slowly becomes no stranger at all. Gradually day and night split up again, you get some sleep (not as much as you would like, for some time) the little one smiles at you, it becomes a person, its days and yours gradually become a familiar shape, the surreal nightmare aspect 'what have I done, why did I do this' begins to fade away. The awful strangeness of it all will pass. Your OP 'a state of shock' is exactly what it is, indeed.
There are wonderful things waiting in store for you. I know you can't see them right now or imagine what they might be, yet. But they do come, and these are things you would never have had without having a child. These rewards truly are waiting in store for you, so hang in there and simply let time pass, minute by minute.
I must just add that second time around I was prepared for all this, yet still didn't much enjoy the first six months. Those first few weeks with a newborn truly are a surreal other world. Yet I would have no hesitation in saying that my children have given me more joy than anything in my life, that I loved having them, and have no regrets. I wish I had had more! The miseries of those early weeks seem just a little thing, viewed in their proper context of a child's whole life, a context you don't have yet in these early days, but it's on its way. And I think it's a safe bet to predict you too will feel the same way - once you've crossed back into real life again, once your little 'alien' becomes a person.
Thinking of you. Wish I could take your little one for a day and night to let you get some sleep! It's partly utter exhaustion that's making you feel this way. That and seeing no hope of any time to yourself, ever again. But that too will come.