I didn't know Lotte was Mrs. Brecht; I did know that she was a noted actress and that she performed in The Threepenny Opera both in Berlin and in New York (maybe elsewhere, too, like maybe London).

What I always found confusing was that her name is in the song; I figure she must have played herself, i.e., that Lotte Lenya was/is a character in the play originally played by the actress Lotte Lenya (but undoubtedly portrayed by others as well).

I never saw or read The Threepenny Opera -- just know some of the songs. And, besides Mack the Knife, I'm not sure which Weill/Brecht songs are from this particular show. Pirate Jenny? Whiskey Bar/Alabama?