I can list here all the things that you could do with your wife to spice things up or to improve your sex life but they don't mean nothing when you have already screwed up.

I ain't here to judge but fact is being sexually frustrated will never justify cheating. There's no way to sugarcoat this but you're officially an asshole to everyone you love and you pretty much deserve every bit of trouble coming your way, sooner or later. Hopefully your paramour's husband is not the physically violent type.

Good luck, TS!