I'm so sorry you had to come here Sammy, but I'm so glad you found us!
Ok, I want you to listen carefully. Some things you will read on here will not make you happy. You will think to yourself "but they don't know him like I do, they didn't see the look in his eyes when he told me xyz, they aren't me, they haven't been in my situation and know what's going on in our lives". But the truth is, we ARE you, we HAVE seen the look in his eyes when he's "confessing", we HAVE been in your situation, and we know exactly where the road you're on leads. So please keep that in mind when reading some of the difficult things you will read.
Some of us are also jaded by our own experiences. So there are definitely going to be some harsh responses at times, but take what you need and leave the rest.
Ok, now to talk about your situation.
I want to tell you that the likelihood that your WH (wayward husband) has told you the truth about his physical encounter is about the same as your chance of winning the lottery tomorrow. The WS almost always minimizes some aspect of the affair, they do it to "protect" the BS (betrayed spouse), and your WH has already lied to "protect" you at least once that you know of. We call this TT, or trickle truth. It's where the real truth comes out a little bit at a time to "spare" us anymore hurt. And it ALWAYS hurts when that TT finally starts to come out. So I want you to be prepared for the day when your WH tells you that he did in fact have sex with that woman while away at work. It is HIGHLY likely to have happened.... and he's also highly likely to swear on your childrens lives that it didn't happen. That's another common tactic that the WS uses, swearing on something you think they would never sully, but they do. ALL cheaters are liars (hence the cheating), so you know for a fact now that he is a liar regardless of what he swears upon that he isn't.
The general consensus around here is that while it is possible to trust your spouse again, you will likely never blindly trust them again. I call it the "trust but verify" trust. I'm almost 6 years out from DDay (the day I discovered my H's infidelities). We're in a very successful R (reconciliation) and he's been a model FWS (former wayward spouse) since the beginning. We did have a bout of TT, but he's been generally awesome since then. Still, I don't blindly trust him at all, and I won't ever again. I do trust him, but I will still check on him on rare occasions just to verify that he's still being honest. He's not happy with himself that I have to verify, but he completely understands it.
For your sanity, and the additional protection of your M (marriage), I highly recommend that you contact the OW's (other woman) husband and tell him what has been going on. Do NOT tell your WH that you are going to do this because VERY often the WS will then contact the AP (affair partner) and tell them what's coming, and the AP will tell their BS that some "crazy jealous person" has been claiming they were cheating with their spouse. This lays the groundwork for the other BS to not believe you, and therefor you get no help in keeping eyes on both AP's to help maintain NC (no contact). The other BS has a right to know what's going on his marriage as well as you do. He also has a right to get STD tested to protect his health as well. It will be difficult to tell him, but it will be beneficial to killing the affair for good. Affairs most often die when they are fully exposed, but not often before that.
Speaking of STD testing, get tested NOW! You have to ask your Dr. for the full panel test, and also specifically ask for Herpes testing as well. Keep in mind that some STD's take months or years to show a positive result. There's a pretty nasty one called HPV that causes cervical cancer in women and throat cancer in men, and it can take YEARS to show up, and there NO test for men for this disease yet. Get tested regardless of what he says because, remember, cheaters are proven liars and you certainly can't trust him about not having sex with her. I would also demand STD testing for WS as well.... H and I both got tested at the same time at the same facility and he was miserable about it.... too bad.
Keep in mind that MC and weekend retreats and such won't work unless he is completely out of his A. If he met her last week, it isn't over yet. He should write a NC letter and send it right away, you should read it first and omit any of those lovey dovey statements that the WS often includes. It's not meant to be a love note, it's meant to be a "geez, I really screwed up and need to work on my marriage so you're no longer allowed in my life in any way shape or form" kind of thing. There are more details about NC letters in the healing library. Read that whole library, it will be worth the time.
Think carefully before inviting WS here, some people find that their WS monitors them on here so they are not free to express their suspicions or concerns without the WS knowing what the BS is watching for.
Ok, I think that's enough for now. I don't want to overwhelm you. It's all information that is good to have and know. Take care of yourself.... eat when you can, drink fluids all the time, and sleep at any chance you get. It's also time to consider some SERIOUS boundaries for when WH is travelling for work because that is the time when he can go and do whatever he wants without thinking you can verify anything. Set your boundaries, and make sure you stick with them. It's hard to do, but necessary.
Take care Sammy, you WILL be ok. No matter what happens to your marriage, you WILL be ok.