I don't want to counteract all the positive support here, but I'd just like to throw in my 2p.
With DS (now 2) I had similar problems to you - agonising pain. DS had a tongue-tie, but also just hated being BF'd The tongue tie was sorted at 6 weeks, but even after that he hated it. I BF'd to 9 weeks, and expressed for a further 8 weeks, and then weaned him on to formula. I beat myself up over the decision to stop BF, and felt really guilty over whether I should do it or not. When I actually made the decision and DS was on formula, I felt so much better. I was dreading the next feed / express, I started to enjoy spending time with DS and I was so much happier. I had lots of positive support along the way, lots of good advice that in the end didn't make a jot of difference!
I've just had DD (she's 3 days old) and BF is working a charm this time - she feeds like a trooper, and although it's sore, it doesn't make me sob while feeding, like it did with DS. It just reminds me of all the heartache I went through when I was struggling with DS.
Sorry, that's all a bit convoluted, but basically what I'm saying is that sometimes, it just doesn't work. If it doesn't work, then do what works for YOU, because your DS probably won't notice a jot whether he has BM or formula, but he will notice whether you're happy or not.
Also definitely get some decent pain relief for your CS scar and get that potential infection looked at. Push for Solpadol/Tramadol ( can make you constipated though) or Diclofenac rather than just OTC co-codamol. Don't settle for any less.
Hope you're feeling better soon, because I really identify with what you're going through!