Well I don’t care what the breed or diagnosis is, but am sorry you are going through this.
Fact of the matter is you bought what you though was going to be a performance/breeding quality dog, and the dog is not only not that quality, but sounds like it will have vet bills in the future. If the dog was going to be ok but only pet quality, I would request that the breeder adjust and refund the purchase price accordingly. If the dog is going to require, say, frequent bloodwork and veterinary management, I would say the breeder should be thankful the pup has a great home and refund all the money.
This is where the small world scenario is actually helpful. If the breeder refuses to cooperate and continues to breed the dogs that produced the defective puppies, I would have no shame in telling people yes, we got a puppy from her, and here’s what happened.
My guess is that the breeder cares more about the $$ than about the breed and the money from selling the puppies is already gone.