Imaculata
Hero
To the OP, if this discussion has made you regret your ruling, then know this:
Speaking both for myself and other DM's that I play with, sometimes we regret how we ruled on something and go back on it. We try to be consistent on the rules as much as possible, but a bad rule can get in the way of fun. So whatever agreements were made at the start of the campaign, we can always change our mind. Nothing stops you from having an honest talk with your players why you feel your ruling may have been in error. In the end the goal should be for everyone to have fun. You are not a monster for making a bad call, we all do on occasion. And I know your players will respect you for changing it, and explaining your reasoning.
Speaking both for myself and other DM's that I play with, sometimes we regret how we ruled on something and go back on it. We try to be consistent on the rules as much as possible, but a bad rule can get in the way of fun. So whatever agreements were made at the start of the campaign, we can always change our mind. Nothing stops you from having an honest talk with your players why you feel your ruling may have been in error. In the end the goal should be for everyone to have fun. You are not a monster for making a bad call, we all do on occasion. And I know your players will respect you for changing it, and explaining your reasoning.