If your birth did not go as planned you should seek out some help as early as possible. I really do mean as early as possible. Asking your GP for a referral to a counselor at your one week or six week postpartum check is the perfect thing to do. You can talk it out while it is still fresh and avoid those conversations that will end with '...but you are healthy and baby are healthy'. Healthy is a state of mind and a state of body.
This comes with a caveat that unless you come across this article you may not even think about this in those early, sleepless, new born days. You may be back at work and finally have some head space to examine your feelings around this. You might be thinking of conceiving again or the pain of difficult birth may not reappear again until you are pregnant. If this is the case I want you to know it is not too late. And most importantly if you had heard those comments above from people that don't quite understand I want you to know that your feelings are valid and you deserve peace around this.
Counselling with a certified psychologist is definitely the best place to start. You need to be heard in a safe space without any judgement. While the quality of care given will have significantly impacted on your experience you also need to find your own part in the birth - it may have been misplaced trust or passive acceptance. It is not that you need to carry a burden of guilt in accepting a role in a traumatic birth but a way to empower yourself to change something for a better experience if you are having more children. For example if you trusted the wrong OB then you can do more research and ask more questions for a subsequent pregnancy so you can have an outcome you want.
The most important thing to remember is that your feelings about the experience is valid. That 'healthy baby / healthy Mama at any cost' is not a healthy mindset and does not account for mental health which is just as important as physical health. Any experience during birth or condition after birth that makes you feel less than whole should be heard and healed.