from when I was young, wild and completely fucking STUPID. Nobody will ever experience this but me.
You were young and carefree. Stop blaming yourself - I swear, you never hear men shaming themselves for their sexual activity when they were young and irresponsible. For them, it's "sowing their wild oats" 🙄
Obviously we don't know what your medical problem is but try and seperate it out from your youthful sex life. Something happened to you which you will always have to life with, whether it was because of actions you did or not it doesn't make you at fault.
Whatever you did, from what you've said, no amount of sex education in the world would have prepared you or warned you for the resulting consequence. So give yourself a break- it sounds as if things are very much hard enough without adding in am unhealthy dose of self-flaggelation.
Life altering diagnoses are so tough and I am so sorry for what it is you are going through. Give yourself time to get your head around the diagnosis and consider some therapy. Even the basic NHS therapists offered by your local gp district will have specialists who are trained to help people come to terms with such things (surprising but true).
And your injury may be something of a unicorn but there will be others who suffer in similar ways, from different causes. You're not alone and don't need to feel humiliated.