I doubt it - I think Jaime's going to tell them himself that Cersei's double-crossing them. That relationship is clearly, quite possibly permanently, broken.
What if Cersei is manipulating Jamie like she did to Tyrion? Maybe she knows Jamie is getting cold feet so she tells him the Euron "plan" and threatened him with the Mountain to drive the point home and send him to Dany with bad info?
Cersi could be trying to get Dany to send whats left of her fleet or a dragon to Bravoss / Euron to split up her forces and then strike her.