Best & Worst Case Scenario if I Dropped a Weight on my Stomach 3 Wks After Tummy Tuck?

I would definitely seek the advice of your surgeon. You could have sustained serious damage to your repair and/or internal organs. However, I am quite surprised that your surgeon would have permitted or condoned lifting this heavy of a weight only 3 weeks after surgery.

Regarding: "3 weeks post op I found myself in the gym. I was working on tricep bench press, became a bit light headed and drop 170 pounds on my upper stomach. I experienced severe pain for the first 20 minutes, then it went away."

So... - you must have been sleep walking and suddenly woke up in a gym lifting 170 pound weights 3 weeks after a Tummy Tuck?

Let's assume that your surgeon forgot to mention to you NOT to engage in any heavy lifting for at least 4 to 6 weeks OR, better yet, let's assume that you did not blatantly disregard your surgeon's instructions when you returned to the gym so soon after your tummy was stitched together...

Worst scenario - the 170 pound weight weakened or tore the muscle repair ( recurrent pooch, bleeding into the muscles, hematoma) and or damaged internal organs

BEST scenario - You got away with such blatantly foolish behavior