I had huge issues over my childrens births.
DD was born prematurely at 32 weeks, was very ill and as a consequence I didn't manage to breastfeed, I often felt guilty (and still do now sometimes just not to the same extent) at kicking up such a fuss at the hospital that they decided to do an exploratory operation and performed a CS at the same time. Many a time I had thought I should've just put up with the pains and left her in a bit longer, maybe then she wouldnt have been so poorly.
DS's birth was a different situation altogether, he was born at 39wks by ELCS, although I had no problems during pregnancy I did feel forced into the CS and wish I'd been more firm/done some research and not let the consultant push me into something I wasn't happy with. That pregnancy wasn't guilt but more the anger everyone has mentioned.
I had DS2 nearly two weeks ago, but spent the whole pregnancy having to make decisions on the birth, doing research into risks etc and ended up having an unwanted, but prepared for ELCS at 41weeks, knowing it was my decision and that no-one forced me into it had given me some closure, as has talking about it.
Birth trauma is very real, and very common but talking about it helps, as, IME, does making sure you are prepared for anything to happen if you give birth again.