I can't tell you how many "HOLY CRAP! That has HOW MANY Calories in it?!" moments I have had after looking at the nutritional info AFTER the fact. Sigh... Sometimes even the healthiest looking things are chock full of calories.
My weight watcher friend turned me on to "dotties website" I think its www. dwlz.com.
She has it inbedded with alot of stuff, but if you scroll down you can find the restaurants button. Even though some things only have the WW "points" values, you can get an idea of the good and bad at places. Basically you want to never go over 10 points, but stay around 6-8 at a restaurant.
I have a personal list of "will never eat there again" restaurants because it seems that there is just nothing even remotely good for you on the menu. Even their supposed "healthy" items.
Here is MY list of banned places:
Chilis
Islands
PF Changs
TGIFridays
Macaroni Grill
Cheesecake factory

Places I WILL go to:
Wildflower bakery and cafe
Paradise bakery cafe
pei wei (you have options to make things lower cal and they have good nutritional info online)
Sweet tomatoes (salad place)
chipotle (because again i can control what goes into my bowl)

Well anyway, don't beat yourself up over the sammich debacle. It happens to the best of us. Just move forward with resolve.
Best of luck!
Denise