Of course you’re feeling happy - you’re acting out that old fantasy of "I should have been with my high school crush! because of course when we’re weirded-out hormonal teens we know exactly what’s best for our lives but naturally we didn’t bother to actually do anything about it then, and so it served as our fall-back fantasies of “soulmates” and all that bullshit " without any of the responsibility of actually, you know, getting married to him, committing to him, going through the day-to-day highs-and-lows of life, the tough stuff, the drudgery, the “for worse” part of “for better or for worse.”
You know, like you do with your husband. The guy who you at one time fell so in love with that you agreed to marry him and share your life with him, to have children with.
I was like you at one point, but I did it before my husband and I got married, and I am grateful every single damned day of my life since then that I wised up and he forgave me. I was stupid enough to think that I was better than him, that I could do better, when that wasn’t the case at all - and no, that’s not a caving-in, “I can’t find anyone better” response of a woman with no self-esteem, it’s me getting better psych help for the depression I was in and was letting twist me because it was easier than facing reality, me rediscovering him, the two of us working to build our relationship together. Reading your justification struck an all-too-familiar chord. Maybe he’s depressed too. Maybe he is worn out by a wife who has to allow herself to be touched, who goes through the motions in sex and can’t bear his touch, but who still claims to love him even with those attitudes towards him and sex with him. That’s not love on your part.
Be honest with yourself - is it depression but rather than looking within yourself or at divorce, are you placing blame on him? You say he’s a good father, but he could be just as good of one if you were divorced. Are you sticking with him for the convenience factor? Extra income? For the built-in babysitter while you’re on a tryst? Do you think your lover would like dealing with young kids (after getting his to teenage years finally) and the responsibilities of marriage again? And are you sure that he really had this “oh we’re soulmates!” fantasy all along, or maybe he was just going along with it because hey, he gets to have sex without the commitment, having to be a stepfather to your kids, and all the bummer stuff about marriage.
Yes, I’m being harsh. Sometimes I think it’s warranted if you get yourself to think about it and what you’re doing. If your husband finds out and decides to divorce you, and assuming this is something that’s important to you, you might well find yourself without primary custody of the kids, especially if his lawyer works the “crazy lady on meds” aspect. Your kids would inevitably hear the “Mommy was cheating on Daddy and made him sad, and I guess she loved that other guy more than her own kids because otherwise she wouldn’t have done that” reasoning, or maybe they’ll start thinking that way down the road.
You have someone you can talk to about this - your psychiatrist/therapist/whatever. And if you haven’t told him/her - why not? Because you’d be persuaded to stop it and analyze yourself about why you’re doing it, right?
Get individual counseling for this. Tell your husband that you want to go to couple’s counseling because obviously things could be better between the two of you. And drop the lover, now. Tell him it’s over and that the two of you can never screw, meet, speak, write, E-mail, call, text, whatever, ever again. I’d fall on the side of not ever revealing the affair to your husband, if only because he doesn’t deserve to be hurt, and typically revealing it also requires some element of remorse, which you don’t have.
Then again, there is merit in letting your husband know exactly what he’s dealing with. Maybe he’ll love you and forgive you, like happened to me, but I actually deeply regretted cheating on my now-husband. And maybe you are tethered to someone who’s beneath you, who doesn’t want to better himself, who you’re better than. Well, then let him see all the cards on the table and figure out for himself if you’re worth staying with.