"The Odyssey" is the first episode where Slade tells Oliver about his son, Joe. He specifically does not say anything about Joe's mother in that episode. If Slade mentions a wife or his son's mother later, I'm not remembering it, but I'm pretty sure he hasn't.

Gretchen's last name is Schwartz, not Black. Schwarz is German for black.

Gretchen's last name is Schwartz, not Black. Schwarz is German for black.