Your post chimed with me as my XH was made redundant (Sep 2008) and then I started my legal studies not long after while holding down a full-time, senior job. We didn't have the challenge of the Atlantic Ocean between us but during my working day and then my studying at weekends there was little time for us to be a couple and XH started a hobby and had an affair with someone he met doing the hobby - idle hands and all that.
I found out 10 months into the affair and he lied and lied and I only found the truth by stealth snooping. He only ever came clean when I presented him with evidence of what I knew and I suspect your H is doing the same. I struggle to believe your H only had an ONS - it's more likely an "on tour" fling and once back home he'd have filed it under "what goes on tour, stays on tour". Successful cheaters are great compartmentalisers and they're the dangerous ones in my opinion.
On his current visit here, did your H behave differently, make you think that something wasn't quite right or were you blissfully unaware and having great reunion sex? If the latter then you have a compartmentaliser on your hands and need to bear that in mind.
If you are going to try and make your marriage work (I tried and threw in the towel after 3 months or so) then be prepared to be fretful when he's not around, on the PC / facebook / texting someone. When he goes to get petrol or a paper and takes 10 minutes longer than normal, you will be wondering if he's on the phone talking to her, and so it goes on.
Don't underestimate just how hard it will to make your marriage work. Your H will need to put in so much work and effort and he must show you over months and months that he's trustworthy. My XH thought that he just had to say sorry once or twice, put on his puppy-dog eyes and that he'd be forgiven. He found my subsequent and endless lack of trust totally intolerable and unreasonable - I think that's because in his eyes he was justified in screwing someone else because I'd stopped massaging his ego.
My point is, if you try to make your marriage work make sure he realises the huge huge huge commitment and effort he has to make and don't think that you will breezily go back to the relaxed, trusting wife you were in the blink of an eye.
As for your upcoming business meetings dig out your sharp suit, sassy shoes - apply your mascara and lippy, don some lovely underwear (always makes be feel fab) then it's tits out, chin up and fake it - you will make it.
Good luck. B&A x