Sorry to see this. This is one of the reasons I've avoided hollow sway bars. But then again, the factory sway bars are also hollow and my front one has been going strong for 14 years. Maybe it's a combination of a hollow bar and the less forgiving polyurethane bushing that breaks them?
Had two APR rear sways fail on me. Second one broke just like that. Removed the first one before it snapped in half, but was cracked in the same area. First was the red one from APR and the other a black one from Hotchkis who made the APR sway bars for the MKV. I moved on to H&R bars because they're solid and have teflon lined bushings which means no grease required and no noise.
i have read a lot of faults, especially in rear sway bars, sold from APR, made by Hotchkis. Is there any type of guarantee? It's a shame for a company of that level.
You're likely outside the warranty period by now. Either put the stock bar back on or find an alternative aftermarket unit. Just another lesson learned on the path.