A workout that I have enjoyed success from came from Huge in a Hurry. Every rep is to be done with perfect form. If the form breaks down the set stops.
Your getting injured because of the form them, not because of fatigue. If you keep training the fatigue will go away if its an injury due to bad form then that's harder to solve.
Basically man up and push through the pain, or stop and quit no other way about it your not going to get fitter otherwise.
As fatigue increases your form will break down. There's no way around that. Any routine that over-emphasizes reps without also stressing consciousness of your form will inevitably lead to injures.
