Welcome to Piecing. I'm afraid (or is it happy?) to be with the "come clean" gang. When my H saw how devastated I was when he just said he was thinking of a D...I pressed about OW...he lied, said it was dinner, kissing, that's it.
I KNEW in my gut that wasn't all there was. It took HER calling our house a few months later for me to get the whole gory story. And then a few more months for the A to end (I thought it already had ) and yet more details to emerge....
Your H is NOT going to like that you've lied this far. But I think it's far better that he know the truth, than continously "wonder" about it. Just read Sage's thread if you have any doubts about that.
Now a complication here is the gender reversal. Did you notice that the one person who voted for keeping it quiet was a man? I wonder if that's because the physical side of A's is so much more painful (generally) for men? Personally, had my H just been out for sex, I would have been pissed, outraged...it was the fact that he was "in love" with OW that tore my heart out.
Now a good question is timing...things are JUST starting to warm up a touch for you two. I can understand you not wanting to broach this and risk severing that fragile bond.
Does he ask about this aspect of your A often? Recently?
You might actually want to rehearse what you will say.
eg: "H, this is so hard for me to admit because I am ashamed, afraid of hurting you even more, afraid of your reaction, afraid you might share this with others (big mistake I made early on! )...but yes, it did get physical with OG...2X in the whole 5 months. It helped me see that he wasn't who I thought, not the one for me (if this is true, and it DOES sound like sex with him wasn't all that great)....He was nowhere near the lover you are etc etc. I DO NOT fantasize about him, he freaks me out and scares me and I wish beyond all wishes that I had never let things go so far!!! I hope by sharing this with you I am helping us BOTH to process this and put it behind us. I know you will need time to deal with this, I hope some day you will find it in your heart to forgive me....
Of course use YOUR words!!!
Now, as I said before timing, mood, the state of your R at the moment is critical. You don't want another trip to the ER!!!
He may challenge you..."how can I believe that's all it was? you lied before"...have a response ready..."H, if I wanted to continue to lie to you, I wouldn't have admitted to this AT ALL...you are the ONLY other person on this planet who knows about this.
Hope some of this helps, only you can make the decision that is right for you.