Sorry but I absolutely disagree with this statement.
That is completely opinionated. Perhaps you feel this way about BALL PYTHONS specifically, but many other snakes should not be fed live, out of safety of the animals - perhaps snakes that are not as strong physically, do not have as strong a feeding response, etc. Each snake is individual. Having a "captive" snake is different than what would be found in the wild, unfortunately (or not?).
I have wanted snakes for a long time and never will I be willing to feed live UNLESS it were absolutely necessary... and I couldn't do it myself, I would have to get someone else to. It would break my heart.
In your situation OP, it is very unfortunate that you believe your BP was not fed enough before you got it. That is difficult for you, and will make switching to f/t difficult as well.
However, it can be done! Don't give up on that if it is really what you want to do.
But what comes first and foremost, as everyone has said, is the health of your snake. There are a tonne of threads on here about how to feed live, and then also how to switch to f/t (which it sounds like you have checked out and tried already).
I don't have any experience feeding live, so I cannot help you there... but I hope everything works out for you, and that your BP takes some food!
Good luck, and don't be discouraged!