I'm so sorry to hear this, I know how painful this is. Others will come along to offer their own words of comfort and excellent advice. I do think you will find this site very helpful.
Right now, consider that you are in a devastated emotional state, probably affecting your body too - take care to eat, drink and sleep enough now, you have to take care of yourself now, extra care. You may not be in a good position to make decisions right now so you should seek out professional advice. I would go to a lawyer and see what divorce looks like for you. You may not consider this at all and you may not have to, but you should know this information for your own safety and it will bring you some comfort that a future, even without your husband, is very possible. We should always be prepared for future problems, especially with finances. Check out some lawyers and go with the one you're most comfortable with that seems to have a good track record. You don't have to share this with your husband. I'd keep a lot of stuff to myself at this point.
I hate to say this, to cause you perhaps more pain, but I think you have to consider that his may well be more than just an emotional affair especially as they have physical access to each other. Many will start off explaining their affair that it was just on line, an emotional affair, just a few kisses....and there's more. This IS something to consider - do not trust what he tells you at this point. Try to verify things if you can. You should check his social media, computer, check the deleted files, and also your financial records to see if he's done any strange spending. I know this is a lot to think about but...hopefully it IS just an emotional affair, not to make that light, but that it's not more enmeshed than that. I would also get an STD test. Yes, this is all the crap that happens when people cheat.
Always remember that he didn't cheat because of you....this isn't your fault. Maybe he wants something different or better or this was an ego boost or whatever, but that's all IN HIS HEAD and nothing you did. Don't accept any blame for this. IMO, people cheat for 2 reasons: 1. Because they want to and 2. Because they think they can get away with it. Keep in mind, also, what YOU want out of a marriage and a spouse and whether he has been living up to those things....or if things are lacking for you in various ways. They often are in cheating relationships. You are the victim here....do whatever it takes to make yourself feel whole....don't primarily consider his feelings or have a "poor baby" attitude....your needs at this point have to take center stage. You may not be used to that position and you need to, if that's true.
The last point I'll make right now is that.....HE SHOULD LEAVE THIS JOB. Obviously people who are cheating with someone should not be seeing that person or engaging with them. If he can leave the job at all, he should. I know times are tough but....it's a practical thing. It's also a consequence. If he can't leave right now, he has to minimize contact and no after work things or events. One thing you have seen, which no doubt has amazed you, as it amazed me.....is that you can't trust him anymore...not for the foreseeable future. You never would have thought he would do this, it was probably unthinkable. It was for me too. But now you know he CAN, so you have to be wary. Once you know, you know, and you can't go back to the way things were before. We all got kicked out of Eden. This is post-Eden.
You WILL get through this, I think you will come out stronger and clearer about your own needs, goals, and boundaries. Have belief in yourself and take care of yourself, put YOU first. Good luck!