I had this experience. There was lots else besides the gay thing going on with him (including narcissism and a horrible temper) but that played a major role. There are lots of misconceptions about gay men, bi men, etc, some on this thread.
Many gay men hop from woman to woman. It's not always about begetting a child. Some are serial users of women, whether to convince others they are straight or to convince themselves. Many will guard their secret as if it was the crown jewels, because for them the secret is the name of the game.
OP if you want to take a look at a support forum, I have PMd you.
You really would care. You really do wonder if it is you or him. It can be really soul destroying to realise you were used and every single day of your life with him was a lie, and it does a number on your concept of yoruself as a woman. Conversely, knowing it was him and there was nothing you could do about it while it does not give you back the time you wasted and yo still feel like the idiot going around with the KICK ME sign on her bum can give yo back your sense of self worth, after you have got through the anger and found a life where you are appreciated fully for yourself, every square inch of you.
My ex landed a GF a good while before we separated. He had several stringing along for a while, all with the same name funny enough. The one he settled on was into theatre in a big way as a performer, and through her he has access to lots of other theatrical people. He was never nice. Even without coming across the gay porn we would have ended up divorcing. He is not happy now. He is still as angry as he ever was.