YANBU at all OP
A terrible terrible mistake was made somewhere, it has led to your body being permanently changed, to long lasting side effects, to your perception on life being altered. I can't imagine how many sleepless nights, cries in the bathroom, moments of sheer worry and panic you and your family have had dealing with this diagnosis. I can't imagine how it felt to stoicly lose a breast to save your life and how you came to terms with that.
Then to find out the diagnosis was wrong, and according to some here you should just skip merrily happy you haven't got cancer, despite being told you had and going through the journey of a cancer patient and having your body permanently altered, now you should apparently be grateful. What a load of unempathetic shit.
You have been done a huge disservice by your consultant. Mistakes happen, terrible ones like this. Your consultant should have made themselves available to you, to answer any and all questions, they should have investigated where the wrong diagnosis came from, explained that to you in full. Unreservedly apologised, explained how their guidance and protocols will change to prevent it happening to anyone else, they should have spoken to you about counciling, about who is now responsible for replacing your implant, about how they will continue to support you for as long as you need them to.
Mistakes do happen, their behaviour after is shameful and unlike and doctor I've worked with. I'd recommend getting your medical notes, contacting for an in depth discussion or debrief and then consulting a medical negligence lawyer to press a case.