Republican (see Joe Barton)
Wasn't that just an affair where his dick got posted as revenge?
Well it wasn't exactly what the thread title is asking for but it's the first thing I thought of when I read the thread title, and it's the closest example I'm aware of of a politician doing this.
Besides, there's a disturbing pattern that many of the same GOPers who trumpet family values are secretly complete and total hypocrites (a lot of the rabid religious right is). Examples other than Barton (who was very socially conservative and pretty much one of the last members of Congress you'd expect this from on paper) include Scott DesJarlais (R-TN04), who's still in office and still apparently 'pro-life' despite asking his mistresses to get abortions, as well as that GOP ex-congressman from Northwest PA who's name I don't remember.