pogre
Legend
This seems like an ideal time to refer your players to some of the old 500-page long falling damage threads!
In all seriousness, it sounds like your players are pushing you if they are threatening to quit the campaign over this. Just be honest and say - I thought the trap was great, but I should have told you the potential damage output beforehand - my mistake. Let's keep playing.
If they threaten to leave if you don't change your ruling and you do change your ruling - it seems like you will have this over your head in what will become a very contentious atmosphere every time you want to make a ruling. That's not a fun situation for a DM IMO.
In all seriousness, it sounds like your players are pushing you if they are threatening to quit the campaign over this. Just be honest and say - I thought the trap was great, but I should have told you the potential damage output beforehand - my mistake. Let's keep playing.
If they threaten to leave if you don't change your ruling and you do change your ruling - it seems like you will have this over your head in what will become a very contentious atmosphere every time you want to make a ruling. That's not a fun situation for a DM IMO.