Protocol fail in the restaurant ( Weight Loss )

I decided on my protocol for food today and really wanted to stick with it. I usually have impromptu meetings and go outside to cafe or restaurants. And that seems to be my weakest spot – going out and eating out. When I am at home, I eat pretty healthy and according to my plan.

C: My husband and I decide to meet at a cafe. He is hungry. I had predecided to order peppermint tea. He asks me if I’d like to share the pizza. I say No – I have had my lunch. He orders the pizza. ( I didn’t order the peppermint tea). Pizza arrives. He eats 80% of it and there are 3 pieces left.
T: I shouldn’t have it.
I want to have it
I have never eaten here.
I can try some.
A slice won’t be too bad.
It’s just a slice.
It will be so yum with chili oil.
I will get to taste it.
I want that taste.
At least I am not having the brownie.
I have had a long day and I deserve a treat.
I will skip dinner later.
I must have it.
He wants me to have it.
It will be rude not to eat with him,
( All these thoughts were going in my head. I couldn’t pinpoint a feeling for these specific thoughts – may be Desire. Temptation. Salivation.
I ended up eating one slice and then another. I could feel like some of these were such excuses as if my mind was forcing me to cave in.

THIS exact phenomenon happens when I go out. And I go out a lot. How do I tackle this in the future and be at ease instead of resisting and fighting these thoughts?