Is it bad????
 

Timing belt just broke on my 1999 A-8 Quattro 4.2. Just how screwed am I? Had a car do this to me years ago and had to replace the heads and valves.

Sounds like you didn't learn your lesson the first time, and now you've gone and made the same mistake again. You ABSOLUTELY need to stick to the timing belt change schedule, or you're in for an expensive repair when that belt breaks on you.

Unfortunately for you the 4.2 engine IS an interference fit engine - meaning when the belt breaks, pistons and valves collide. At the very least, this engine will most likely require new heads at this point. What's more likely to happen is you'll find a used engine to swap into your car (replace the timing belt on the used engine before installation if you don't know FOR SURE when it was last changed); or you're going to sell/part/scrap what's left of your current car, and go find a replacement vehicle.

At any rate, learn from this mistake this time - and don't make this mistake again! If you drive a car with a timing belt, make sure it is changed at the mileage that the manufacture suggests.