Explosive decompression and "lung damage"
One needs to be careful when consulting with internet references about aeromedical definitions such as explosive decompression. As a flight surgeon I was taught it simply meant decompression of an aircraft which takes less than 0.5 seconds. That is considered by most authorities to be “explosive”.
In a series of 184 explosive decompressions in US Navy aircraft, there was only one case of a pneumothorax (collapsed lung). Airliners have a much larger cabin volume and the risk of a pneumothorax during explosive decompression is even lower. I cannot find a case of a civilian airliner decompression survivor with a pneumothorax in the medical literature since 1972. There is a risk, especially as some people are already prone to pneumothorax at sea level, but it must be a rare event in airliner decompressions.
If you elect to take altitude chamber training, which I highly recommend, you will be exposed to an true explosive decompression without your mask at an altitude of 25,000 feet. You'll see all the stigmata of explosive decompression and your lungs will not explode, money-back guaranteed. They could demonstrate it at higher altitudes, but there's a chance you may not get your mask back on fast enough.
Avoid the burrito especialle and beer for supper the night before - that was a mistake I made once.