Patty -
I read about ur case just now, sorry I can't help much giving you specific advice on your case, as my GC route was different (not family based). You seem to be such a nice person, I just couldn't help tell you a few things (and I'm no Dr.Phil)..
You must stop worrying at once! P..L..E..A..S..E
As a_usc nicely put it on the other thread, everything that has happened, has happened already. So be brave and decide firmly before you go to your interview (which is nearly a month away) what story you want to stick with.
I was looking for a thread which some one posted a long time ago, about coming here on a tourist visa from Phillipines and getting married in the US to her long time love (USC) and finally getting her GC. I just couldn't find it. I wish I could show it to you, so your concerns will ease a bit.
There are tons of people who had entered on a tourist visa, accidentally(?!) found some one here, got married and got their GC. At least, your case is legitimate. If you don't panic [and stop using the word "devastated"

] and be strong, it is unlikely that you would get denied.
I want to say a lot of things that will boost your confidence and not make you feel stressed about this situation. But I have a feeling, ultimately it is in your hands. I was in a super mess when I got my CZ, just about the way you feel now or even worse. There were people who supported me and others who said I was going to be deported. But inside, I was strong and was willing to take a risk and everything worked out good. I hope it is the case with you too.
Be positive and think you are going to be fine at the interview. Most likely, you will be!!
Now cheer up!
GOOD LUCK!