I want to add if I may, my experience with a man hasn't happened (As an adult anyway... Another story), but have shared a lot online.
I decided NOT to lie or cheat on This wife of 16yrs. She will NEVER trust me if I lie, She will very likely find out, unless I slip it in a massage, but I can't meet anyone without lying about where I am. Anger and Contempt will build. And it's SHITTY at best w/ her.
When she found my panty collection that got the conversations started. Slowly I'm finding and extending the boundary line.
It would go quicker if I would have been more up front earlier, she says... But I know better, she is 1000 times better about the panties, but it has been just short of one year... I had to convince her to trust me again she thought I discovered I was gay and was looking to leave her. I left her to wonder what I was hiding? I dropped just a few syllables here and there about men and my acceptance of the MM community... etc.. She heard shit I NEVER said... Another special issue that will never go away... She was in an open marriage (Before me... Figures,,, All the luck) BUT it ended very badly... Wrecked lives. So mine will be slow and arduous plus I also have to rebuild some trust cuz I was online, hiding panties and taking pics to post, I had to show her many folders of pics of me... Now it's ok for me to be online chatting. She knows it's with men and women. Doesn't ask details now...
If I were you, I would say to her ... Something like I'm not gay, and it sounds like you are not wanting to leave her to pursue a life w/ men...You will have to show her you love her and this is a sexual fantasy that has developed over the last xx months..Doesn't mean you want to do it but you want to explore it with her as a shared fantasy. Sometimes that satisfies a fantasy, tell her.
She is capable of understanding, but not if I lie.... I cheated on my last wife and my first wife cheated on me... So it goes...