Well Henry is now aware of Jefferson if he overheard him talk to the queen. That is what i meant. So hopefully he told all of that to Emma. He doesn’t need to understand about what happened before to tell Emma what he heard.
And like i said Emma probably didn’t tell him about what happened before, but now that she believes she can tell him that he is the Mad Hatter and that Grace is his daughter. Though honestly the show is going to be completely different now.