Exploding Sink

Our A/C condensate drain has been clogged up. Luckily, we had paid the A/C guy extra to add a ball valve and schrader valve to the line to make cleaning it out a breeze. I should know better, none of my projects are a breeze! I climbed up in the attic to attach the hose and Amber stood on the ground with control of the air valve. I got it connected and told her to go. I could hear air moving, so I figured it worked. She started yelling, stop! STOP! Turns out all the gunk in the line (and it was substantial) made it down to the bathroom sink, but it decided to turn up toward the walls, ceiling, and everywhere instead of stay down in the drain where it was welcome. We managed to get it all cleaned up, but I scrubbed the paint off the walls in some places. And how in the hell do you clean popcorn textured ceiling? Here are some pictures of the mess: