I have very little sympathy for the Republicans right now. They've made their bed and now they have to lie in it. And they deserve it.
That said I don't think the Democrats are any better. In '83 Massachusetts Representative Gerry Studds was caught doing the exact same thing as Foley. Well not exactly. Studds actually had a prolonged affair with a 17 year-old male page, instead of just being a sicko over email. Studds was censured by the House, which he essentially ignored, and served 5 more terms in office until he retired in 1997.
Compare that to Foley, who has already resigned, or Dan Crane, another Republican Representative implicated in the '83 sex scandal who was defeated for re-election after having sex with a 17 year-old female page.
I'll try to track down a link to sex scandals over the years, but suffice it to say that with Republicans the scandal always destroys their careers. I have yet to find an exception (but one may exist). With Democrats, they often get away with it. So all this righteous indignation from the left really comes off as just so much hypocrisy to me.
UPDATE: Gary Hart was a Democrat who lost his career to a sex scandal. Democrats do still have career-ending sex scandals, but they do not always have them. But for Republicans, at least on the national level, sex scandals always end their career and I have yet to find an exception to that rule.