DESPERATE HOUSEWIVES - "Dress Big" - Susan discovers some revealing secrets about her future in-laws, Gaby has a devastating catastrophe at her home, and an unexpected love affair develops on Wisteria Lane, on "Desperate Housewives," SUNDAY, APRIL 8 (9:00-10:01 p.m., ET) on the ABC Television Network. (ABC/RON TOM) NICOLLETTE SHERIDAN, EVA LONGORIA