I was terrified! But you will be fine, I promise 
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Even if your birth doesn't go to plan and all the things you are worried about happen, you will still be fine. I couldn't agree more with what dialm calls 'the zone'. You just get on with it because you have to, and time passes so much quicker than you can possibly imagine because you do sort of just zone out of it all. With hindsight my birth was pretty shitty and lots of the early stage did not go how I wanted, and then ended up with an emcs and DD in scbu for 5 days but I coped so much better than I thought I would, and I am the biggest wuss in the world and both DP and I were convinced I would never cope with labour! Remember that for once in your life the pain is for a good reason (the best!) but if you really do find it that painful then there are magical things such as epidurals to help you. Don't ever, ever feel as though you are wimping out or not doing a great job if you opt for pain relief! It is your birth, after all, and you do whatever you need to.
I actually slept more in the first week of having my baby home than I had done in a long time! Babies sleep a lot, so if you sleep when they do that helps, and of course get your DP to help as you physically recover from the birth. Yes, you might not get 8 hours solid for a while but some babies do go 5, 6 hours or more from quite a young age. The biggest piece of advice I could give any new mum is to work on 'bedtime' and 'nighttime' from as early as possible. You might then get an hour or two to yourself in the evenings, which is magical if you want it. And you very, very soon learn to feel refreshed after just 5 hours straight!
And yes, I'll be honest, you might be miserable sometimes. It can be overwhelming. Your baby sadly hasn't read the books. You probably will screw up on occasion. You might even clock 'em around the head with a hairbrush while trying to multitask 
... But please remember that this is all normal and anyone who says otherwise is lying. You'll also have a life because LO's are amazingly portable for the first few months - it just might be a slightly different life than you had before.
DD is just about to turn 11 weeks. I go out almost every day to meet other mums. Last week I had a boozy night out and a baby-free hungover morning complete with a shopping trip. I made it to my best friend's baby shower when DD was 3 weeks old as she stayed at home with my DP. I've just planned my first night away, for a few weeks time. Life can continue as normal, especially if you take all the help on offer and also let DP do his share (or family).
Just take every day as it comes and acknowledge the miserable, stressy times when they occur (nothing worse than hiding it and not asking for some help or just a hug) and I promise you, it will be wonderful and so will you!