To get some idea of what happened to those in the Titan, you could take a look at what happened in a diving rig working from the “Byford Dolphin” drilling platform. This is somewhat the reverse of what happened last week. “Saturation” divers were living and working at a pressure of 9 bar when their rig was accidentally depressurised. Caution for the faint-hearted – some of this makes grizzly reading:
https://history.howstuffworks.com/historical-events/byford-dolphin-accident.htm
The Byford Dolphin incident resulted from a rapid decompression from nine to one bar. The Titan incident involved a pressure change of more than forty times that magnitude. When it imploded, the air and everything else inside it were suddenly exposed to pressure approaching 400 bar (that is, 400 times normal atmospheric pressure). The air would have been superheated by this compression (think how warm the end of a bicycle pump gets) and the spaces in the humans’ bodies – many full of air and other gases - would have been similarly crushed.
The good news is that all this probably happened faster than the signals from the victims’ senses could reach their brain. They would have had no notice of their impending doom.