What are the odds!!

[Grey Acumen]

sad that I couldn't have seen this thread sooner, as my advice would have been to just ignore the thing, and forget about the 19 year old. If you were only talking to her at the church, that doesn't automatically mean you're cheating. Quite frankly, I'd say your own reaction to this whole thing is what is going to make that look far worse than it was.
Also, from your own words; "I took my secret love out for the last time. I figured, what's the point. She's 19. I'm 31. It could never be more than a fling. Yesterday morning, she calls me. Tells me she wants to spend the day with me. Without thinking, I say yes."
Right there, you've got a problem. You're going "Oh, i wasn't planning on doing anything, honest" sure, but you also weren't planning on having anything to do with her at all after that, yet your first reaction was "sure"

Hate to say it (I don't really, but I feel like I'm expected to) but that's just not going to hack it. You were on your way to pick up your daughter and you end up talking for an hour? What about your daughter? You need to go over your priorities: Family > other people is usually the way that needs to work, and that 19 year old needs to BE "other people"
Saying that you're going to quit isn't the same as quitting. You can't expect a cigarette to become flame resistant just cause you told it you weren't going to smoke anymore.

And don't think I'm just bashing on you here. I had basically declared my relationship with my ex dead, but was still sleeping with her when I was getting involved with the woman who is now my fiance. Thing is, I came clean to my fiance about the issue on my own, and made things clear to my ex that everything was over with her. It still took me a good couple months to get back in my fiance's good graces, and even longer to forgive myself.
But there's the thing, I wasn't going "Aw, damn, I got caught, how terrible!" I was going "Damn, how could I have done that to begin with? how terrible!"

If getting caught is the only thing stopping you, you're going to screw yourself over. There will ALWAYS be a point at which you say to yourself "Hmm... nobody'll find out this one time..." You've got to recognize that the act itself is where the problem is, not the "getting caught" part.