Exactly 3yrs ago tonight, I posted the very same thread. I'd had a terrible labour and delivery first time round and I was up, in labour with dc2. I was terrified. Of the pain, of letting down dd by having another, of having ptsd/pnd again. I shook and cried and the first time round came flooding back.
To be honest with you, the labour went the same way and I had a repeat emcs BUT BUT BUT, it was a very positive experience. I knew categorically from first time round and I am telling you this now, you cannot control the method of delivery and your need for pain relief. You aren't the only person doing this. Your baby is there too and hasn't read any of the books. When in labour with ds, I kept reminding myself that I was doing it WITH him, if HE needed help and HE got stuck and we had to find a different way, then we'd do it together. My second labour was longer but didn't hurt the way the first labour did actually. I didn't need any pain relief and I wasn't out of control at any point so even though he got into the same difficulties as his sister and an emcs was required again, I didn't experience labour in the same way at all.
I'm currently cuddling my very nearly 2yo and that night seems a lifetime ago. The method by which he entered the world is irrelevant to who he is and who we are together. He has completed our family and his labour was a brief sneeze of time.
If you need pain relief, take it. Don't let the first weeks and months of your baby's life be crippled by ptsd caused by out of control pain. I've been there. Your comfort is important, your mental health takes precedence over the untenable goal of the perfect delivery. Perfect is subjective. Make decisions based on how you feel and what you need, not on what you think you arbitrarily should do.
If it helps, I'm here and thinking of you. You will be fine. This is the beginning of something very exciting. No guilt. Take a deep breath and know that it won't be forever.