Hi Alicia!
It was the episode "Ides of Metropolis", season 1.
Clark's secret was that Jonathan believed that Martha had an affair with her art teacher.
Lois's secret could probably be that she's harboring Eugene, but I can't remember for sure.
Maybe this link freshes your memory a little...
http://www.redboots.net/Episodes/season_1c.htm (Although you can't find soooo much information... anyway.)
See you soon.
AnnaBtG.
P.S.: I'm looking forward to this new idea of yours to come true!
