If his wife has genital herpes and he's having sexual contact with others besides her, he really needs to get tested to know his own status. To me it's irresponsible for him not to do so.
The risk of contracting genital herpes from a one time protected encounter are very, very low. It's really not even worth follow up testing from this encounter to be honest. Now if you've never been tested for herpes before to know your own status, do it now with the test jess recommended while it's on your mind.
grace
this happened about 10 days ago. he has never shown any signs of a break out, maybe i am being paranoid.
When did the affair happen? Its unlikely that you got herpes from him, especially if you don't know if he has it or not, but we can't tell you if its too soon without knowing when it happened.
It can take up to 4 months to show positive on a blood test (and make sure you get a type specific IgG blood test, and don't let them give you an IgM), but many people test positive sooner.
I would also ask the guy to test with the same test. If he's negative, you won't have to worry.
Aj
The wife is on daily therapy and it is unkown whether he has it or not.