OP - just to reassure you that a horrific first birth doesn't mean it'll be the same second time round.
My first labour was horrendous and very traumatic. In a nutshell - back to back baby, 24hr labour, failed ventouse and forceps. I'd wanted a hypnobirth (ha) so felt like an utter failure. Afterwards, DS and I were also in a bad way physically and it took a while to recover.
I was petrified of giving birth again and started a thread on here very much like yours, wondering if I should go for an ELCS.
In the end, I'm so glad I didn't. My DD arrived in the birthing pool with just a bit of gas and air, four hours after first twinge and an hour after arriving at hospital. It was calm, painful, but utterly amazing - the absolute opposite of first time round.
My advice to you would be to reassure yourself that there's every chance it'll be easier this time. It's not about mindset or pain thresholds IMO, it's largely luck and positioning. A bad experience last time definitely doesn't have to mean a bad one this time.
I sincerely hope that if you do go for a vaginal birth you're as lucky as I was,but I also completely get why you'd want an ELCS.