There are times that strangers can give better advice than close friends. Since they are not in any mean bias in the situation. In a way, you'll have plenty of advises that you might not think of.
One thing that is a major problem that makes it harder for you is the fact your husband is not a communicator. One sided conversation is never successful. And not to add the silent treatment is far worst.
I would have been more aggressive in him going to Vegas. I am not saying Vegas is a horrible place but it is party place. Like the saying goes, "what goes on in Vegas stays in Vegas."
Have you talked to him about what is it that he is lacking in the marriage that he is seeking it with his friends? Can he not take you out and do stuff together? And is all his friends married or singles?
Why is it that he can talk to his girl (co-worker) for a long time and can't do the same with you?
When your husband said that he goes out and intentionally meet girls with his friends, that is disrespectful no matter how one looks at it. He does need to consider that he has a wife at home. And how does he feel if you do the same thing.
He said he is not cheating on you, but his action contradicts his words. And I know you want to believe it, but the more you see it with your own eyes the difficult it gets trying to convince yourself.
Have a good discussion...if you guys have to argue to get him to talk than so be it. Sometimes, in the heat of an arguement things does come out. It seemed like you have been patient and hanging onto hope.
If you still love him see it through until there's no other way..but a way out. Try it until your hands are completely tied....and when you do walk away...make sure there is no regrets.
****I read your post a few days ago. As I am typing this, I am trying to remember your story*****