I've had this experience too, OP, well...except for the pushing and hell breaking loose.

I would say either find a new class, pick a different spot, or just be a little more polite when you stand your ground. When I've felt hemmed in by people in zumba, I force myself to just focus on the music and the moves, and assume people will get out of my way. If they don't, I apologize for bumping them but usually it takes just one bump for someone to get the hint and move over a little. I definitely wouldn't push someone if i were you. Are you sure you're allowed to come back to that class after hell breaking loose?