I was absolutely terrified of giving birth too. I think what kept me together was actually the fact I was in complete denial that I'd ever actually have a baby. Stupid I know!
When I went to my antenatal classes at the hospital I very nearly fainted when we talked about the birthing process. I mean I obviously new it was going to happen but I hadn't envisaged it before then.
TBQH I think I spent the whole time in denial and never really prepared myself. I had an idea of what I wanted but didn't want to make set plans because I knew i'd find it stressful if it went differently.
In the end I had a very long labour. It was 68 hours of regular contractions starting at 10 minutes apart. It was exhausting and very painful but I knew it wasn't going to kill me. I ended up being allowed to stay in hospital when I got to 7cm and only ended up having a couple of hours of gas and air. I was quite surprised by how I coped and that I didn't have much pain relief.
My mum is also the most squeamish person I have ever met and she managed to give birth to my sister and me (we're twins) vaginally.
If we can both do it, I'm sure you can too. But if it really is a serious fear and you can't come to terms with it, maybe you could consider talking to your mw about an elective cs. It's by no means an easy option but you may find that it's right for you.
Good luck with whatever you choose. 