When things do not go as planned, and you have to break the news to those who have helped, to those who have offered their ideas, their energy, their work, there is one thing that can make it worse.
Blaming the change of plan to others.
Of course, it works in the moment. It pushes away the shame for the loss, the difficult conversation, the necessary argument.
But as you regroup and start delivering against the new plan, no one will feel committed.
Find a reason to believe in instead, and motivate the changes with passion. Even when it was not you making the call, especially when it was not you making the call. Nobody likes change, but everyone is willing to accept it, if it makes sense.
Long term is always more important than short term. That is the distinctive sign of leadership.