Miss Stephanie reports it better when she says:
Atticus didn’t bat an eye, just took out his handkerchief and wiped his face and stood there and let Mr. Ewell call him names wild horses could not bring her to repeat.
Isn't that amazing! What character! I love how in this moment Atticus has absolutely no problem turning the other cheek. He allowed Ewell to do this because he understood that he had hurt Ewell's reputation (as if he had one worth protecting in the first place) during the trial.
The two also exchanged words. Because Atticus didn't make any effort to physically defend himself Ewell asked if he was too proud. Atticus merely responds, "No, too old." The children struggled with this response and hoped Atticus would consider carrying a gun since they think it could happen again.