Bonnie Kaye, who had a website for straight spouses said she had spoken to, can't remember exactly but I'm thinking maybe 3000 straight wives and not one of them turned out to be wrong in wondering if their husband was gay.  something like that, just remember reading it and thinking oh, well add me to the statistics.

Gay in denial, it's a thing.  It is all around the place.

Same as you, I didn't think he could be doing anything behind my back, we lived together, worked together and socialised together.  Since leaving I have met someone who had regular coffees in town with him, there was a whole group of them would get together and my ex never said one word about it to me at all.  My friend was shocked when we put two and two together and he had to recognise that the nightmare wife he had heard all these (false) stories about was actually me who he knew quite well by then and liked.  I was shocked both to discover my ex had been doing things behind my back I really did not think it possible and also how long it had been going on and how bad the gaslighting was, still find it shocking.
 
Sorry to say but everything you say does add up to thinking your husband is in the closet.  Your instinct is nagging at you (mine did that too) and all I can think is third wife, he has probably got very clever at hiding his tracks.  

Yes me too - I always thought it was something wrong with me too - not him.

I'd asked him if he was gay before but he always said no and finally I think why didn't the first no satisfy me so I looked on line found this forum and that is when I learned the term gay in denial.

The way I approached him was to ask if he was bisexual, that worked for a bit, he didn't deny it, he talked about it, he said it meant he could choose who he wanted, it meant he was special, and it wasn't any of my business.  I maintained he wasn't straight and he should have told me.  After two weeks, yes two whole weeks of talking about this he says he's changed his mind, he is 100% straight and if I think different that would make me crazy.

It was a threat.  I got divorced as fast as I could.  It was my solicitor who said to me you do realise he is being emotionally abusive and financially abusive don't you.  

So my advice is not to approach him, don't bother.  Give yourself the benefit of the doubt not him.  Stop thinking of him as a partner and give yourself a hug, keep your counsel like you did before you got married, look for friends and family you can talk to.  

One good thing I did was straightaway I took back paying the bills and managing our joint bank account which he had been doing for the last little while.