WASHINGTON (AFP) - Embattled US Senator John Ensign anno-unced Thursday he will resign in May after getting embroiled in a sex and corruption scandal that saw him become the subject of an ethics probe. It is with tremendous sadness that I officially hand over the Senate seat that I have held for eleven years, the Nevada Republican said in a statement. I stand behind my firm belief that I have not violated any law, rule, or standard of conduct of the Senate, and I have fought to prove this publicly, he said. (But) I will not continue to subject my family, my constituents or the Senate to any further rounds of investigation, depositions, drawn out proceedings or especially public hearings. The 53-year-old lawmaker cited the ongoing investigation into his handling of an affair with former aide Cynthia Hampton, whose husband Doug had been Ensigns administrative assistant. He said the investigation had caused simply too great an emotional cost to him and his family. The Senate Ethics Committee is investigating claims that Ensign violated ethics rules and federal law after his affair. Ensign acknowledged the affair in 2009, after Doug Hampton threatened to go public.